**Reason**:
SkelJS has been created by Ori Livneh as a showcase to write JavaScript for MediaWiki. It hasn't received code since September 2012. As an example, it does not work out of the box with NodeJS 6: T196506
The BoilerPlate extension might be a better fit and it is actively maintained.
- [x] Archive documentation on `mediawiki.org` ( https://www.mediawiki.org/wiki/Extension:SkelJS )
- [x] Remove from `mediawiki/extensions` ( along with in `.gitmodules`)
- [X] Remove tests in `integration/config` ( `zuul/layout.yaml` )
- [x] Remove from `translatewiki` ( `groups/MediaWiki/mediawiki-extensions.txt` )
- [X] Empty repository and add a OBSOLETE file.
- [X] Archive the extension's diffusion repository: ( https://phabricator.wikimedia.org/diffusion/ESJS/ )
- [X] Mark the repository read-only in Gerrit: ( https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/SkelJS )
- [X] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-SkelJS