See
<https://www.mediawiki.org/wiki/MediaWiki_1.21/wmf6#Breaking_changes>
<https://www.mediawiki.org/wiki/MediaWiki_1.21/Roadmap#Schedule_for_the_deployments>
Is someone taking care of these notifications? Please help
1) checking that the instructions are clear and complete (e.g. what
updates are needed for custom enotif_body),
2) listing the affected wikis.
Note that it's also very unclear what sort of changes are legally
allowed for wikimedia-copyrightwarning, some wikis like it.wiki have
changed the copyright/terms of use warnings drastically (besides adding
tons of other crap) but the legal department only checks/advises en.wiki.
Unless for some mysterious reason a wiki is very sure of how it should
be, my personal suggestion is to keep the default, but as such I didn't
write it on the wiki page.
Nemo