[Qgis-community-team] Processing help

[Alexander Bruy]

Done, results available in my repo, branch processing-help [0].
Almost all help files are just templates, but TauDEM is fully
documented.

Also I add some guidelines to documentation guidelines document.

Comments and suggestions about are welcome. When we will be
happy with results I merge this into main documenation repo.

[0] https://github.com/alexbruy/QGIS-Documentation/tree/processing-help

-- 
Alexander Bruy