feat(pm/wiki): allow category membership tracking

From https://www.mediawiki.org/wiki/Manual:CategoryMembershipChanges,
under https://creativecommons.org/licenses/by-sa/4.0/
> Catwatch is a MediaWiki feature that tracks category membership
> changes. It is possible to view these changes in the recent changes
> and watchlists.

packetmix/systems/teal/wiki.nix

···
 
       $wgSVGNativeRendering = true;
 
+      $wgRCWatchCategoryMembership = true;
+
       $wgShowExceptionDetails = true;
       $wgDevelopmentWarnings = true;
     '';