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.