Add documentation for ``pyreverse`` and ``symilar``

[DudeNr33]

Is your feature request related to a problem? Please describe

pyreverse is an awesome tool to visualize the project structure and dependencies.
However, it is not even mentioned once in the documentation.
I think adding at least some basic instructions on how to use it and what the output looks like would make it a bit more widely known.

Probably symilar should get a few sentences as well, but I must admit that I do not know if it is really intended to be used from the command line directly?

The last console script which gets installed additionally to pylint is epylint. I do not think that it needs additional documentation, since as I understand it its main purpose is the integration with Emacs, which is already described properly in the docs.

Describe the solution you'd like

Add documentation pages for at least pyreverse, probably also symilar.

You can assign this issue directly to me, if you want.

[Pierre-Sassoulas]

I agree, we need more documentation (in general too, but for pyreverse in particular). Especially if there is a new fancy plantuml option 😄