Add documentation for cool flags

[abh3po]

we have some really cool flags and they can be mixed to do some really awesome stuff like coala -I -b <SOMEBEARNAME> -B gives the info about the given Bear, we should document this!

[jayvdb]

@shreyans800755 @abhsag24 , can you work out what is missing and where it should go, so that this request is actionable.

[shreyans800755]

@abhsag24 Are you sure about this command ?

When I tried following command: coala -I -b ClangBear -B it gives list of names of all the bears.

I'm working on other PR which can print details only for the selected bears using option --bears. Ref https://github.com/coala/coala/pull/4832.

[pydevsg]

I am willing to work on this issue Can I be assigned this @jayvdb