The following rendering modules are based on Doxia:
xwiki-rendering-syntax-doxia
xwiki-rendering-syntax-apt
xwiki-rendering-syntax-docbook
xwiki-rendering-syntax-twiki
None of them are packaged in XWiki Standard and I doubt any are really used much in practice (or ever were to be honest). Doxia 2 started to do some clean and removed support for docbook and twiki and I think we should start to do the same thing.
+1 to move them to contrib, ideally creating one repo per module. However this would mean a dep on a released version of the doxia module and a re-release of all the modules when the doxia module changes, so not sure in the end. Maybe a single repo is the best after all, idk.
“to their own repository” means one repo for each (In French: “… de bouger tous les modules concernant Doxia dans leur repository”). Indeed, the mention of a single GH repo was contradictory.