docs: split readme file

[sergelogvinov]

Update installation instructions. Add controllers explanations.

Pull Request

What? (description)

Why? (reasoning)

Acceptance

Please use the following checklist:

• [ ] you linked an issue (if applicable)
• [ ] you included tests (if applicable)
• [x] you ran conformance (make conformance)
• [ ] you linted your code (make lint)
• [ ] you linted your code (make unit)

See make help for a description of the available targets.

[sergelogvinov]

/m