gh-149906: Update README with details on CPython internals

[Szhenger]

Technical Documentation: Extended Python/README and convert to Markdown

• Updated the Python/ directory README to provide more context on the compiler and runtime execution logic.
• Converted the file to README.md to support hyperlinking to the internal documentation.
• Added relative links to the InternalDocs directory.

• Issue: Request update for Python/README #149906

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[sergey-miryanov]

This is a documentation change, so we don't need a NEWS entry—please remove it.

Overall, I don't think this change is worth making.

[Szhenger]

That is fair, while reading the Python module, I believed it would be helpful for new contributors to get redirected to more verbose resources.

[Andrew5057]

Why specifically interpreter.md? There are other internal docs that might be relevant; compiler.md comes to mind. What I'm getting at here is that the specific choice of docs to link is pretty arbitrary, and deciding to select only a couple implies that the other ones aren't very relevant, which isn't true.

Plus, the top-level README.rst already links to the Developer Guide, and the InternalDocs directory is visible from the top level.

[Szhenger]

I agree with that assessment, I should have pointed to both the compiler.md and the interpreter.md since this module does describe the execution of the compiler and interpreter functionality. Certainly both should have been considered. Since the Internal Documentation is at the high level, I thought it would be useful for the current README to be updated to reflect the Internal Documentation's existence since the current version of the file is quite broad.

I'll close my pull request because you make a good point on replication. Do y'all think the Python/README should be left alone or modified since I'm a little unconvinced that it is just miscellaneous source files for the Python shared library is descriptive enough?