Readthedocs build instructions

[edwardchalstrey1]

TODO:

• Add instructions for pushing the changes to readthedocs, since this may currently be a manual step
  • @tturocy @rahulsavani how is this currently done? This would be good to automate - see Don't run GitHub actions unless needed and add pre-commit alan-turing-institute/gambit_admin#2

[tturocy]

This is configured on the readthedocs side, so those builds are automated once we've pushed to GitHub. But that only works for branches we've activated. So testing the build online for proposed changes isn't as straightforward - one can of course build locally but that requires installing sphinx and in any event sometimes the local builds work and then the online one doesn't because of environment differences.

[edwardchalstrey1]

This is configured on the readthedocs side, so those builds are automated once we've pushed to GitHub. But that only works for branches we've activated. So testing the build online for proposed changes isn't as straightforward - one can of course build locally but that requires installing sphinx and in any event sometimes the local builds work and then the online one doesn't because of environment differences.

Great, thanks for explaining, I've opened #543 to look into automating this, in the meantime I think we can merge these local build instructions that worked for me