There seems to have been no actual development activity on the spreadsheet extension in 5 years (May 2013), mostly just the upstream changes to it's git submodules, as they're unpinned
Time for it to go away?
- [x] Archive Extension documentation page on [mediawiki.org](https://www.mediawiki.org). <https://www.mediawiki.org/wiki/Extension:Spreadsheet>
- [ ] Remove submodule from `mediawiki/extensions.git`.
- [ ] Remove Jenkins pipeline from `zuul/layout.yaml` file in `integration/config.git`.
- [ ] Remove extension from `groups/MediaWiki/mediawiki-extensions.txt` file in `translatewiki.net`.
- [ ] Empty repository, leaving only a note in the README file.
- [ ] Archive Phabricator project for the extension.
- [ ] Edit Phabricator project description, and add link to this ticket.
- [ ] Mark the repository read-only in Gerrit, and prefix description with `[ARCHIVED] `.
- [ ] Archive the repo mirror in Phabricator Diffusion.
- [ ] Delete the repo mirror on GitHub.com.