This commit adds a guide to AIO navigation for
"Migrating to Version 9" and moves the schematics
section into the guide that previously lived in
the deprecations page. It also pastes a snippet
of the deprecations page in the new guide so users
don't have to filter out deprecations they've seen
before.
Note: Ivy compatibility section is coming up in a
follow-up PR.
PR Close#33339
Kara Erickson