Clarify bit type in setbit/getbit documentation

[dsoprea]

Calling it 'boolean' is misleading in the context of Python.

Pull Request check-list

Please make sure to review and check all of these items:

• [N] Does $ tox pass with this change (including linting)? Missing support for all Python versions on local
• [Y] Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• [Y] Is the new or changed code fully tested?
• [Y] Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• [NA] Is there an example added to the examples folder (if applicable)?
• [N] Was the change added to CHANGES file?

NOTE: these things are not required to open a PR and can be done
afterwards / while the PR is open.

Description of change

Clarified certain types cited in the setbit/getbit comments->documentation.