Document the various code generation tools used by CPython

Describe the enhancement or feature you'd like

There should be some documentation about the various code generation tools used in CPython, for example:

• freeze_modules.py
• deepfreeze.py
• generate_global_objects.py

I don't think there needs to be a massive amount of documentation about these. Just a brief mention of their purposes, how to invoke them, and notes about their related make targets.

Related are the Parser generator etc., which are already documented under Guide to CPython's Parser, but could also be mentioned. I think their existing docs could also be used as something of a template.

Describe alternatives you've considered

Argument clinic is already documented at https://docs.python.org/3/howto/clinic.html so maybe this documentation would be more appropriate in the main Python repo's docs? I'll defer to the devguide maintainers on this.

Additional context

Started from a conversation at https://github.com/python/cpython/pull/30941#issuecomment-1023501086

CC @ericisnowcurrently

Review the existing Guide to CPython's Parser section and the listed tools: freeze_modules.py, deepfreeze.py, and generate_global_objects.py. Determine whether the documentation belongs in the devguide or CPython's docs, then document each tool's purpose, invocation, and related make targets, with parser-generator links where appropriate.