[Python] fix docstring to comply with PEP 287

[MMurape]

[Python] fix docstring to comply with PEP 287

The python template predominantly uses PEP 287 - reStructuredText (reST) format style docstrings for function documentation. However certain functions docstrings - namely in modules/swagger-codegen/src/main/resources/python/api.mustache and modules/swagger-codegen/src/main/resources/python/api_client.mustache - are in syntactic and or grammatical violation of the correct convention.

Useful links:

• https://peps.python.org/pep-0287/
• https://www.sphinx-doc.org/en/master/usage/domains/python.html#info-field-lists

I proposed a solution in pull request #12533