Move out documentation to ReadTheDocs

[aik099]

Over time documentation became pretty extensive, and having it in a single README.md file creates these problems:

1. harder to find specific command documentation
2. harder to trace if specific command documentation is up to date with the actual command (each command changes README.md)
3. almost impossible to understand how to install the App, because instructions are at the bottom of the file.

Need to:

1. move out documentation into the "docs" folder with each command description located into its own file
2. connect ReadTheDocs