**Reason**:
Not deployed anywhere according to wikiapiary.
Does not seem to have receive any new code since the initial import
- [ ] Archive documentation on `mediawiki.org` https://www.mediawiki.org/wiki/Extension:Semantic_Genealogy
- [ ] Remove from `mediawiki/extensions` / `mediawiki/skins` ( along with in `.gitmodules`)
- [ ] Remove tests in `integration/config` ( `zuul/layout.yaml` )
- [ ] Remove from `translatewiki` ( `groups/MediaWiki/mediawiki-extensions.txt` )
- [ ] Remove manifest/other references from `mediawiki/vagrant` if they exist
- [ ] Empty repository and add a OBSOLETE file.
- [ ] Archive the extension's diffusion repository: rEGNE
- [ ] Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/SemanticGenealogy
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-SemanticGenealogy