Provide some documentation and promotion around the upcoming changes in T148514
Announcements have been made here:
https://pl.wikipedia.org/wiki/Wikipedia:Kawiarenka/Kwestie_techniczne#Improving_Wikipedia_branding_on_mobile
https://it.wikipedia.org/wiki/Wikipedia:Bar/Discussioni/Improving_our_Wikipedia_branding_on_mobile
https://ca.wikipedia.org/wiki/Viquipèdia:La_taverna/Propostes
https://sv.wikipedia.org/wiki/Wikipedia:Bybrunnen#Improving_our_Wikipedia_branding_on_mobile