Add a stable branch for building docs

[caleb-johnson]

The serverless docs say they reference the latest version released to pip, as they draw the version # from that release; however, the docs are currently built from the main branch, which means the docs do not reflect the version they say they do.

It would probably be better to have a stable branch from which to build the docs

[psschwei]

In other projects, we've cut branches for each minor release (e.g. v0.2, v0.3, etc.) and then cherrypicked patches in if we needed to do a dot release. Looking at qiskit-terra, that seems to be how they do it as well.

[psschwei]

There will probably be a non-trivial amount of updates needed to the CI (which isn't to say we shouldn't do it, just that it might require some thinking around how to implement it)

[psschwei]

I'd leave it open -- it's something that still needs to be implemented, so this gives us a nice place to track/discuss.

[Tansito]

Not 100% directly related but today I started with #764 so we can think in something similar

[psschwei]

Another option might be to move the docs to their own repo

[Tansito]

I would not disagree with that option. It would be my preferred one.

[psschwei]

Sounds like the solution is to move to a new repo (xref #1166), so we can probably close this one.

[IceKhan13]

I think so. Closing