✨(frontend) create generic theme

By default Docs will not be on the dsfr theme but
on the generic theme. La Gaufre is part of the dsfr
theme and is removed from the generic theme.
Same for the "beta" keyword and the "proconnect"
buttons.

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to
 - ✨(backend) integrate maleware_detection from django-lasuite #936
 - 🏗️(frontend) Footer configurable #959
 - 🩺(CI) add lint spell mistakes #954
+- ✨(frontend) create generic theme #792
 - 🛂(frontend) block edition to not connected users #945
 - 🚸 Let loader during upload analyze #984