Getting Started Guide 🎉 (#530)

* Update index.md

Created a Getting Started Guide

* Getting Started Guide

Updates made basted on feedback from Jared.

* Getting Started Guide

Added Sections 6 and 7 Compression and Caching

* Getting Started

Added example to #3.

* Getting Started Guide

Updated example

* Getting Started Guide

Updated the title of #7

docs/getting-started/index.md

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-# Getting Started Guide
+# Getting Started Guide
+
+Keyv provides a consistent interface for key-value storage across multiple backends via storage adapters. It supports TTL based expiry, making it suitable as a cache or a persistent key-value store. Follow the steps below to get you up and running.
+
+## 1. Make a Project Directory
+Make a directory with your project in it.
+
+```sh
+mkdir keyv
+cd keyv
+```
+You’re now inside your project’s directory.
+
+## 2. Install keyv
+
+```sh
+npm install --save keyv
+```
+By default, everything is stored in memory; you can optionally also install a storage adapter; choose one from the following:
+
+```sh
+npm install --save @keyv/redis
+npm install --save @keyv/mongo
+npm install --save @keyv/sqlite
+npm install --save @keyv/postgres
+npm install --save @keyv/mysql
+npm install --save @keyv/etcd
+```
+
+> **Note**: You can also use third-party storage adapters
+
+The following are third-party storage adapters compatible with Keyv:
+- [`quick-lru`](https://github.com/sindresorhus/quick-lru) - Simple "Least Recently Used" (LRU) cache
+- [`keyv-file`](https://github.com/zaaack/keyv-file) - File system storage adapter for Keyv
+- [`keyv-dynamodb`](https://www.npmjs.com/package/keyv-dynamodb) - DynamoDB storage adapter for Keyv
+- [`keyv-lru`](https://www.npmjs.com/package/keyv-lru) - LRU storage adapter for Keyv
+- [`keyv-null`](https://www.npmjs.com/package/keyv-null) - Null storage adapter for Keyv
+- [`keyv-firestore`](https://github.com/goto-bus-stop/keyv-firestore) – Firebase Cloud Firestore adapter for Keyv
+- [`keyv-mssql`](https://github.com/pmorgan3/keyv-mssql) - Microsoft Sql Server adapter for Keyv
+- [`keyv-azuretable`](https://github.com/howlowck/keyv-azuretable) - Azure Table Storage/API adapter for Keyv
+
+
+## 3. Create a New Keyv Instance
+Pass your connection string if applicable. Keyv will automatically load the correct storage adapter. ////
+```js
+// example Keyv instance that uses sqlite storage adapter
+const keyv = new Keyv('sqlite://path/to/database.sqlite');
+```
+
+
+`Keyv` Parameters
+
+Parameter | Type | Required | Description
+------------ | ------------- | ------------- | -------------
+uri | String | N | The connection string URI. Merged into the options object as options.uri. Default value: undefined
+options | Object | N | The options object is also passed through to the storage adapter. See the table below for a list of available options.
+
+`options` Parameters
+
+Parameter | Type | Required | Description
+------------ | ------------- | ------------- | -------------
+namespace | String | N | Namespace for the current instance.  Default: 'keyv'
+ttl | Number | N | This is the default TTL, it can be overridden by specifying a TTL on .set().  Default: undefined
+compression | @keyv/compress\-\<compression_package_name> | N | Compression package to use. See Compression for more details. Default: undefined.
+serialize | Function | N | A custom serialization function. Default: JSONB.stringify
+deserialize | Function | N | A custom deserialization function. Default: JSONB.parse
+store | Storage adapter instance | N | The storage adapter instance to be used by Keyv. Default: new Map()
+adapter | String | N | Specify an adapter to use. e.g 'redis' or 'mongodb'. Default: undefined
+
+### Example - Create an Instance of Keyv with a connection URI
+The following example shows how you would create and Instance of Keyv with a `mongodb` connection URI.
+
+```js
+const Keyv = require('keyv');
+
+const keyv = new Keyv('mongodb://user:pass@localhost:27017/dbname');
+
+// Handle DB connection errors
+keyv.on('error', err => console.log('Connection Error', err));
+```
+### Example - Create an Instance of Keyv using a third-party storage adapter
+
+[`quick-lru`](https://github.com/sindresorhus/quick-lru) is a third-party module that implements the Map API.
+
+```js
+const Keyv = require('keyv');
+const QuickLRU = require('quick-lru');
+
+const lru = new QuickLRU({ maxSize: 1000 });
+const keyv = new Keyv({ store: lru });
+
+// Handle DB connection errors
+keyv.on('error', err => console.log('Connection Error', err));
+```
+
+## 4. Create Some Key Value Pairs
+
+Method: `set(key, value, [ttl])` - Set a value for a specified key.
+
+Parameter | Type | Required | Description
+------------ | ------------- | ------------- | -------------
+key | String | Y | Unique identifier which is used to look up the value. Keys are persistent by default.
+value | Any  | Y | Data value associated with the key
+ttl | Number | N | Expiry time in milliseconds
+
+The following example code shows you how to create a key-value pair using the `set` method.
+
+```js
+
+const keyv = new Keyv('redis://user:pass@localhost:6379');
+
+// set a key value pair that expires in 1000 milliseconds
+await keyv.set('foo', 'expires in 1 second', 1000); // true
+
+// set a key value pair that never expires
+await keyv.set('bar', 'never expires'); // true
+```
+
+
+
+Method: `delete(key)` - Deletes an entry.
+
+Parameter | Type | Required | Description
+------------ | ------------- | ------------- | -------------
+key | String | Y | Unique identifier which is used to look up the value. Returns `true `if the key existed, `false` if not.
+
+To delete a key value pair use the `delete(key)` method as shown below:
+
+```js
+// Delete the key value pair for the 'foo' key
+await keyv.delete('foo'); // true
+```
+
+
+## 5. Advanced - Use Namespaces to Avoid Key Collisions
+You can namespace your Keyv instance to avoid key collisions and allow you to clear only a certain namespace while using the same database.
+
+The example code below creates two namespaces, 'users' and 'cache' and creates a key value pair using the key 'foo' in both namespaces, it also shows how to delete all values in a specified namespace.
+
+```js
+const users = new Keyv('redis://user:pass@localhost:6379', { namespace: 'users' });
+const cache = new Keyv('redis://user:pass@localhost:6379', { namespace: 'cache' });
+
+// Set a key-value pair using the key 'foo' in both namespaces
+await users.set('foo', 'users'); // returns true
+await cache.set('foo', 'cache'); // returns true
+
+// Retrieve a Value
+await users.get('foo'); // returns 'users'
+await cache.get('foo'); // returns 'cache'
+
+// Delete all values for the specified namespace
+await users.clear();
+```
+
+## 6. Advanced - Enable Compression
+
+Keyv supports both `gzip` and `brotli` methods of compression. Before you can enable compression, you will need to install the compression package:
+
+```sh
+npm install --save keyv @keyv/compress-gzip
+```
+
+### Example - Enable Gzip compression
+To enable compression, pass the `compression` option to the constructor.
+
+```js
+const KeyvGzip = require('@keyv/compress-gzip');
+const Keyv = require('keyv');
+
+const keyvGzip = new KeyvGzip();
+const keyv = new Keyv({ compression: KeyvGzip });
+```
+
+You can also pass a custom compression function to the compression option. Custom compression functions must follow the pattern of the official compression adapter (see below for further information).
+
+### Want to build your own?
+
+Great! Keyv is designed to be easily extended. You can build your own compression adapter by following the pattern of the official compression adapters based on this interface:
+
+```js
+interface CompressionAdapter {
+	async compress(value: any, options?: any);
+	async decompress(value: any, options?: any);
+	async serialize(value: any);
+	async deserialize(value: any);
+}
+```
+
+#### Test your custom compression adapter
+In addition to the interface, you can test it with our compression test suite using `@keyv/test-suite`:
+
+```js
+const {keyvCompresstionTests} = require('@keyv/test-suite');
+const KeyvGzip = require('@keyv/compress-gzip');
+
+keyvCompresstionTests(test, new KeyvGzip());
+```
+
+## 7. Advanced - Extend your own Module with Keyv
+Keyv can be easily embedded into other modules to add cache support.
+- Caching will work in memory by default, and users can also install a Keyv storage adapter and pass in a connection string or any other storage that implements the Map API.
+- You should also set a namespace for your module to safely call `.clear()` without clearing unrelated app data.
+
+>**Note**:
+> The recommended pattern is to expose a cache option in your module's options which is passed through to Keyv.
+
+### Example - Add Cache Support to a Module
+
+1. Install whichever storage adapter you will be using, `keyv-redis` in this example
+```sh
+npm install --save keyv-redis
+```
+2. Declare the Module with the cache controlled by a Keyv instance
+```js
+class AwesomeModule {
+	constructor(opts) {
+		this.cache = new Keyv({
+			uri: typeof opts.cache === 'string' && opts.cache,
+			store: typeof opts.cache !== 'string' && opts.cache,
+			namespace: 'awesome-module'  
+		});
+	}
+}
+```
+
+3. Create an Instance of the Module with caching support
+```js
+const AwesomeModule = require('awesome-module');
+const awesomeModule = new AwesomeModule({ cache: 'redis://localhost' });
+```