Make "build pull requests" configurable via .readthedocs.yaml

[sajith]

This is a feature request, and not an issue as such, so I'm omitting "details", "expected result", and "actual result". Sorry about that!

This is the feature I wish to see:

"Build pull requests" is a very useful feature when someone wants to contribute to a project's documentation using GitHub pull requests. Currently a project owner is expected to turn on this feature via the readthedocs.org's web UI.

It would be useful if a project could add some lines like below to its .readthedocs.yaml:

github:
  build_pull_requests: true

Not exactly like that, not necessarily, but you get the idea. This would helpful if someone prefers doing things semi-programmatically.

From v2 schema, it doesn't seem that this is possible today. I was told in the Gitter channel that this is indeed the case.

(I am submitting this on behalf of tahoe-lafs project, in case that detail is useful. We have a similar wish about configuration of automation rules as well, but let us first see if the seemingly simple thing is feasible!)

[stsewd]

So, for now we are currently using the config file for options that are valid per-version instead of global options, there is another feature request related to using a global option inside the config file #4221

[stsewd]

Closing this in favor of #6046