rename .readthedocs.yml to .readthedocs.yaml

[sgbaird]

The content looks like it's been updated to the new configuration format (https://github.com/pyscaffold/pyscaffold/blob/master/src/pyscaffold/templates/rtd_cfg.template); the file just isn't named what I expected based on the docs. I recently ran into issues with building on sphinx due to using the old file format. Maybe it doesn't matter to readthedocs if it's .yml vs. .yaml, but I figured I'd bring it up.

https://colab.research.google.com/gist/sgbaird/6e503e7f069260b039d6e86aeaf62721/pyscaffold-rtd-cfg-file.ipynb

Purpose

Rename .readthedocs.yml to .readthedocs.yaml to be consistent with the readthedocs docs https://docs.readthedocs.io/en/stable/config-file/v2.html

#727

Approach

Rename file

[coveralls]

coverage: 97.936%. remained the same when pulling dd66513 on sgbaird:patch-3 into 14ff855 on pyscaffold:master.

[abravalheri]

Hi @sgbaird, thank you very much for opening this issue and providing a PR.
Can you describe the errors you were seeing?

In principle it should not matter if we use .yml or .yaml based on these docs (also the RTD documentation itself seems to use a .yml), but there is no problem in changing it to match what is documented. I just want to make sure there is nothing else we need to change.

[sgbaird]

@abravalheri you're right, shouldn't be an issue either way. I think .readthedocs.yaml can get confused with the prior format (it did for me at least), but not a major issue.

[sgbaird]

I can close if you want.