simple start for the README

[yegor256]

see #631

[yegor256]

@fizruk please, take a look

[deemp]

@yegor256 @fizruk, this initial version of README is OK.

However, I think the output of all commands should be provided in the README. Ideally, the output should be generated automatically via a tool like mdsh.

Automating the README updates can be done in another PR.

[yegor256]

@deemp I suggest keeping README as simple as possible, making it play the role of a motivator not a reference manual. The user should be able to understand how to do a few basic operations and get the results that the user expects. When additional information will be required, the user may go to another place (the website, for example). However, this will happen rarely, I believe (taking into account the fact that there are just a few users and all of them are in our team).