gh-119786: move interpreter doc from devguide to InternalDocs

[iritkatriel]

Reorganised index:
https://github.com/python/cpython/blob/7cb14417f5609f75ab484bc81885930158317336/InternalDocs/README.md

Interpreter doc:
https://github.com/python/cpython/blob/7cb14417f5609f75ab484bc81885930158317336/InternalDocs/interpreter.md

• Issue: create an internals documentation folder in the cpython repo #119786

[willingc]

Thanks @iritkatriel. I love that the internals docs are next to the code 😄

[AlexWaygood]

I think you might be able to get away with just this (also applies to a bunch of other links in this PR):

Suggested change

	Recall that the [Python Compiler](https://github.com/python/cpython/blob/main/InternalDocs/compiler.md)
	produces a [`CodeObject`](https://github.com/python/cpython/blob/main/InternalDocs/code_object.md),
	Recall that the [Python Compiler](compiler.md) produces a [`CodeObject`](code_object.md),

[iritkatriel]

I guess I could also use relative links to the code (like ../Python/bytecodes.c).

[AlexWaygood]

Try it and see how it renders? You can get a good preview of how GitHub will render it by pushing to this PR branch, then clicking this "View file" button here from the "files changed" tab:

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[AlexWaygood]

Nice! A couple of minor things I spotted:

[willingc]

🚢