docs: Update ReadTheDocs (rtd) configuration

[JST5000]

High Level Overview of Change

ReadTheDocs has some breaking changes that need to be updated before September 15th.

Context of Change

• Adds build > os (a new required field as of October 25th) https://blog.readthedocs.com/use-build-os-config/

Also fixes a misnamed

Type of Change

• [X] Documentation Updates

Did you update CHANGELOG.md?

• [X] No, this change does not impact library users

Test Plan

Builds locally and by inspection follows the new rules.

[ckniffen]

Will this fix the theme?

[JST5000]

Will this fix the theme?

No, I don't think so, I'll do that in a separate PR. I think that has to do with the conf.py setup.