Help:Diff

What's the history of the diff?
Why would we use a diff view? (History)

Exceptionally good examples of documentation

 * https://www.mediawiki.org/wiki/Help:Extension:Media_Viewer
 * External: https://stripe.com/docs/billing/subscriptions/overview

Tips for documentation writing in general
https://www.mediawiki.org/wiki/Documentation/Style_guide