Quick start should focus on usage, not examples

[JaniAnttonen]

Quick start should be converted to a quick guide on how to:

1. install &
2. import &
3. use

...the web components in a production setting instead of running the ready-made examples

[JaniAnttonen]

For example, "Once you have a Payment Pointer address to your wallet, update its value into paymentPointer property in examples/audioAndVideo/config.js — or examples/text/config.js if your media is text." doesn't apply in a regular use case.