Add advice to get the best user support (will need backport)

This commit contains a list of things to do when you want to get the best user support. It's more like a wishlist than anything.

Except for that, the commit also includes several smaller changes throughout the page.

WIP because I want to check in Sphinx it before merging. The Edit mode is really useful, but I changed some more advanced things so I need to check the syntax.