Multi-version documentation

[AVHopp]

This PR introduces the multi-version documentation.

The logic is the following:

• A new branch gh-pages was created. On this branch, the actual documentation is hosted. For each version of the documentation, including stable and latest, there is one folder containing the actual documentation. This makes the folders reachable via URLs once the settings in the repository have changed.
• As of now, the latest stable version is included for "backwards compatibility". Note however that this version does not yet contain the version selector and won't until the next release!
• There are two different cases in which the new docs workflow will be triggered:

1. There was a push to main: This rebuilds the latest folder and updates it.
2. There was a release: This updates the folders latest, stable and X.Y.Z, where X.Y.Z is the tag that was used in the release.

• Whenever any folder other than stable is being created, an announcement banner saying that this is not the stable version is included. Also, a "version selector" is injected, showing both the current version and providing a link to the (currently not nice looking) page for switching the version.
• The gh-pages branch was designed such that it is as minimal as possible. Thus, all actual python scripts and logic is contained in the actual branch and is being copied from main whenever the documentation is built.
• NOTE: This does not yet fix the issue of having the proper README.md appear on the github page for technical reasons. Happy to explain the detailed reasons via a meeting or here if you are interested.

For testing, I created the exact same Pull Request as well as as "dummy release" on my fork and merged both of these/created a new release, so please have a look at https://avhopp.github.io/baybe_dev/stable/ for details.

[Scienfitz]

does this need any preparation? this repo has enver had the corresponding branch used unlike the fork so I wonder whether anything is implicitly expected/needed or should it just work flat out?

[AVHopp]

Regarding stuff that still needs to be changed on the repo side:

• There is already a prepared gh-pages branch in this repo
• We only need to change the settings in this repo to deploy from that branch instead of using github actions.

[AdrianSosic]

Hi @AVHopp, thanks for getting this to work 👍🏼 I'm also currently trying to get the lockfile running, and then we have all missing pieces ready for a first multi-version doc!

[AdrianSosic]

Hi @AVHopp. Thanks for taking care of this. There is so much custom html stuff involved that it is really hard for me to review. But the main requirement are:

1. it does its job
2. you've tested it
3. the code is in a clean enough form for you so that you won't freak out when we notice that another change is required in 2 weeks time :D

So I guess all that is fulfilled, so accept 🚀

[AdrianSosic]

I think the hotfix logic is not yet explained in the PR description?

[AVHopp]

Will include, do you want to check it then or just have it for the sake of it being documented?