Delete extension authoring docs
Created by: vdavid
Closes https://github.com/sourcegraph/sourcegraph/issues/40991
Co-author: @philipp-spiess
There were three parts to solving this issue:
- Make sure there are deprecation notices on each extension page
- Delete "authoring extensions" section
- Add "deprecated" badges to menus
In this PR:
- Deprecation notices were all in place, so no changes were needed.
- Deleted "authoring extensions" pages, including all references to them. We also needed to rephrase a few parts in the docs to remove extension mentions.
- Didn't need to add any badges to the content because there were no in-line menus. On the left and right sides, there are menus that list extension-related pages, but those are part of the Sourcegraph docs engine rather than the content. I decided it brought too little compared to the effort needed to add badges there.
Test plan
Go through the docs as reviewers and see if they look fine