Add commands to the 'Writing Documentation' section

[decentral1se]

On the Write documentation section, I couldn't find exactly how to get started easily.

I was able to find out what I need to do:

$ tox -e docs
$ firefox doc/en/_build/index.html

Then I could check my changes locally. I think it might be nice to add a note in the 'Writing documentation' section for those commands, especially for people not used to working with tox/sphinx/looking in the setup.cfg.

Or it's written somewhere else?

I'll submit a PR if that is useful 🍻

[nicoddemus]

I'll submit a PR if that is useful

Yes please! We have decided for tox -e docs to be the official command for building documentation locally but never got around to write it somewhere.