Rewrote adoc to markdown (#1867)

- rewrote diktat-cli.adoc to README.md

README.md

@@ -43,9 +43,7 @@ Main features of diktat are the following:
 
 4) **Strict detailed [Codestyle](info/guide/diktat-coding-convention.md)** that you can adopt and use in your project.
 
-## Run as CLI-application
-
-[Info](diktat-cli/diktat-cli.adoc)
+## Run as [CLI-application](diktat-cli/README.md)
 
 ### Download binary
 

diktat-cli/README.md

@@ -0,0 +1,49 @@
+# _diktat-cli_, the command-line client for [_diktat_](https://github.com/saveourtool/diktat)
+
+---
+
+# Table of contents
+1. [Features](#features)
+2. [Usage](#usage)
+3. [Option summary](#option-summary)
+4. [Exit code](#exit-codes)
+
+---
+
+## Features
+
+* Self-executable JAR in _UNIX Shell_ (requires installed _JAVA_)
+* BSD-compatible
+* Also works in Windows (_Git Bash_, _Cygwin_, or _MSys2_) via the dedicated _diktat.cmd_
+* Can be used as a regular uber JAR
+
+## Usage
+
+```shell
+diktat [OPTION]... [FILE]...
+```
+
+## Option summary
+
+| Command-line switch                  | Meaning                                                                                                                                                                                                                |
+|:-------------------------------------|:-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `-c CONFIG`, `--config=CONFIG`       | Specify the location of the YAML configuration file. By default, `diktat-analysis.yml` in the current directory is used.                                                                                               |
+| `-m MODE`, `--mode MODE`             | Mode of `diktat` controls that `diktat` fixes or only finds any deviations from the code style.                                                                                                                        |
+| `-r REPORTER`, `--reporter=REPORTER` | The reporter to use to errors to `output`, one of: `plain`, `plain_group_by_file`, `json`, `sarif`, `checkstyle`, `html`.                                                                                              |
+| `-o OUTPUT`, `--output=OUTPUT`       | Redirect the reporter output to a file. Must be provided when the reporter is provided.                                                                                                                                |
+| `--group-by-file`                    | A flag to group found errors by files.                                                                                                                                                                                 |
+| `--color COLOR`                      | Colorize the output, one of: `BLACK`, `RED`, `GREEN`, `YELLOW`, `BLUE`, `MAGENTA`, `CYAN`, `LIGHT_GRAY`, `DARK_GRAY`, `LIGHT_RED`, `LIGHT_GREEN`, `LIGHT_YELLOW`, `LIGHT_BLUE`, `LIGHT_MAGENTA`, `LIGHT_CYAN`, `WHITE` |
+| `-l`, `--log-level`                  | Control the log level.                                                                                                                                                                                                 |
+| `-h`, `--help`                       | Display the help text and exit.                                                                                                                                                                                        |
+| `-l`, `--license`                    | Display the license and exit.                                                                                                                                                                                          |
+| `-v`, `--verbose`                    | Enable the verbose output.                                                                                                                                                                                             |
+| `-V`, `--version`                    | Output version information and exit.                                                                                                                                                                                   |
+
+## Exit codes
+
+| Exit code | Meaning                                                                                                             |
+|:----------|:--------------------------------------------------------------------------------------------------------------------|
+| 0         | _diKTat_ found no errors in your code                                                                               |
+| 1         | _diKTat_ reported some errors in your code                                                                          |
+| 2         | The JVM was not found (probably, you need to set up the JVM explicitly, using the `JAVA_HOME` environment variable) |
+| 3         | Incompatible _Bash_ version                                                                                         |