Finish migration from subdomains to subdirectories

Things that will need to be cared for:

Convert project redot-docs-live to redot-docs-live-dev, associated with docs-dev.redotengine.org, that only listens to develop branch
Create new project 'redot-docs-live' that only listens to main branch
Remove: rewrite rule that converts docs.redotengine.org/lang/branch to docs-branch.redotengine.org/
Change root HTML from test page to redirect
Cloudflare project that redirects from docs to docs-stable
Disassociate docs.redotengine.org
Attach docs.redotengine to redot-live

After test period:

Redot-Engine / redot-docs