[BUG]: Enable `test_docs.py` and `doctests` tox environment in `test-docs.yml` workflow

[nfelt14]

Description of the bug

Currently there is no test for documentation that comprehensively checks builds and links in the documentation. See https://github.com/tektronix/tm_devices/blob/main/tests/test_docs.py for a good example of the test file.

Steps To Reproduce

Run tox -e doctests

Environment Information

No response

Additional Information

No response