Remove docs (16)

[a-velasco]

Documentation for PostgreSQL 16 has moved to the 16/docs branch of the postgresql-single-kernel-library repository.

This PR removes all Sphinx Stack (Starter Pack) documentation and tooling.

All URLs to the docs being removed are automatically redirected to the newest domain.

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[carlcsaposs-canonical]

is the git history of the 16/docs branch of postgresql-single-kernel-library as expected? it looks like it contains code & workflows

also we might want to enable rulesets for branch protection on the docs branches

[a-velasco]

is the git history of the 16/docs branch of postgresql-single-kernel-library as expected? it looks like it contains code & workflows

also we might want to enable rulesets for branch protection on the docs branches

Yes, all of this is expected/known. The 16/docs branch in single-kernel is getting cleaned up, and I need push permissions to both /docs branches for the moment.

[taurus-forever]

Maybe we should leave breadcrumbs to the new documentation location for people who want to contribute...