Update contribution guide with a new label (patch)

This patch label aims at identifying small Merge Requests containing warning or build error fixes, small updates of comments, documentations or logs, removal of commented parts ...

It indicates that the author would like to merge it without dashboard testing (if reviewers agree).

It shall be clear for reviewers that when they give a +1 for a "patch" merge request, it also means "ok for a merge without dashboard testing"

added 1 commit

• 9cf3af2c - DOC: patch label -> request to merge without dashboard

Compare with previous version

Now explicitly stated.

merged

mentioned in commit e80d0b6a