Documentation includes static list of contributors, not updated

[alexisvl]

All the documentation contains something like this:

*Contributors*

Jean-Pierre Charras, Fabrizio Tappero.

Quite a few more people have contributed documentation, but nobody remembers to add names to the list. Perhaps we can either remove the explicit lists in favor of just referring to "the KiCad documentation contributors", or find a way to have that pulled out of the git history automatically?