In order to allow our Scylla OSS customers the ability to select a version for their documentation, we are migrating the Scylla docs content to the Scylla OSS repository. This PR covers the following points of the [Migration Plan](https://docs.google.com/document/d/15yBf39j15hgUVvjeuGR4MCbYeArqZrO1ir-z_1Urc6A/edit#):
1. Creates a subdirectory for dev docs: /docs/dev
2. Moves the existing dev doc content in the scylla repo to /docs/dev, but keep Alternator docs in /docs.
3. Flattens the structure in /docs/dev (remove the subfolders).
4. Adds redirects from `scylla.docs.scylladb.com/<version>/<document>` to `https://github.com/scylladb/scylla/blob/master/docs/dev/<document>.md`
5. Excludes publishing docs for /docs/devs.
1. Enter the docs folder with `cd docs`.
2. Run `make redirects`.
3. Enter the docs folder and run `make preview`. The docs should build without warnings.
4. Open http://127.0.0.1:5500 in your browser. You shoul donly see the alternator docs.
5. Open http://127.0.0.1:5500/stable/design-notes/IDL.html in your browser. It should redirect you to https://github.com/scylladb/scylla/blob/master/docs/dev/IDL.md and raise a 404 error since this PR is not merged yet.
6. Surf the `docs/dev` folder. It should have all the scylla project internal docs without subdirectories.
Closes#10873
* github.com:scylladb/scylla:
Update docs/conf.py
Update docs/dev/protocols.md
Update docs/dev/README.md
Update docs/dev/README.md
Update docs/conf.py
Fix broken links
Remove source folder
Add redirections
Move dev docs to docs/dev
973d2a58d0