- update config availablility/deprecation notes
- add notes on metadata inconsistency during config v3 migrations
- use update instead of upgrade for v2 migration for consistency
- fix external link opening
GitOrigin-RevId: a8ca31948285f55a5fac8d00b93f85007be512cc
* remove unused css (using purgecss but also checking results manually)
* remove unused fonts
* remove unused examples_schema_migrations dir
* remove underscore & bootstrap pagination
* remove unused djangodocs files
* clean up djangodocs.css
* organize static files (move to _static/scripts and _static/styles)
* clean up and organize scripts (move out of layout.html and into hdocs.js)
* defer scripts that can be deferred
* remove global_tabs extension & files and replace with tabs directive in the only place it's used