* Fix Sphinx warning in library/xml.rst
Direct use of the pyexpat module is deprecated, but this is how to check the version for security purposes
* Fix Sphinx warning in library/importlib.resources.rst
* Use italics for parameters
* Link to the exception
* Fix Sphinx warning in library/gzip.rst
* Document message and header defect base classes to fix Sphinx warning in library/email.headerregistry.rst
* Restore feed_eof() doc to fix Sphinx warning in library/asyncio-stream.rst
* Fix Sphinx warning in extending/newtypes.rst
* Fix Sphinx warning in c-api/set.rst
On stdtypes.rst, set and frozenset are documented together and the frozenset has the working refs
If an HTTP link is redirected to a same looking HTTPS link, the latter can
be used directly without changes in readability and behavior.
It protects from a men-in-the-middle attack.
This change does not affect Python examples.
* Separate out files relating to importlib.resources
* Update Introduction to direct readers to the submodule documentation.
* Create separate file for abcs relating to resources.
* Move abc docs back to where they were.