Is your feature request related to a problem? Please describe.
Describe the solution you'd like
MediaWiki has its extension and skin system. Each extension or skin exists on its repository and is released separated by the MediaWiki core.

• Anyone can create and maintain an extension or skin.
• The version number is recorded at skin.json or extension.json file.

I want to use Release Please for it.

Describe alternatives you've considered
I have created a fork and am using it.
Additional context
There is no standardized CHANGELOG.md convention. In further, it seems the developers of MediaWiki ecosystem commonly do not write anything.

• Extension:Notifications (previously "Echo") - https://github.com/wikimedia/mediawiki-extensions-Echo/blob/master/RELEASE_NOTES
• Extension:Wikibase - https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/master/RELEASE-NOTES-1.44
• Vector, DiscussionTools, GrowthExperiments, etc. have no notes
  https://github.com/wikimedia/mediawiki-skins-Vector
  https://github.com/wikimedia/mediawiki-extensions-DiscussionTools
  https://github.com/wikimedia/mediawiki-extensions-GrowthExperiments
  https://github.com/wikimedia/mediawiki-extensions-Chart