azure-communication-phonenumbers needs docstring updates for sphinx

[azure-sdk]

ACTION NEEDED: All sphinx errors and warnings must be fixed by 2024-04-15. The build will begin to fail for this library if errors are not fixed.

This issue indicates that your library reference documentation is rendering with errors. To avoid customer issues, please ensure you take care of these errors and warnings ASAP.

Library name: azure-communication-phonenumbers
Sphinx build: Link to build (2024-06-17)
How to fix: Run the strict-sphinx tox command at the library package-level and resolve the docstring errors and warnings.

1. ../azure-communication-phonenumbers>pip install "tox<5"

2. ../azure-communication-phonenumbers>tox run -e strict-sphinx -c ../../../eng/tox/tox.ini --root .

3. Once resolved, set strict_sphinx = true in the package's pyproject.toml file.

See Sphinx and docstring checker for more information.