Lint: fixup subsubsection markups

[erlend-aasland]

Consistently use ^ iso. ' markups for subsubsections

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📚 Documentation preview 📚: https://cpython-devguide--1239.org.readthedocs.build/

[erlend-aasland]

Discovered over at #1238.

[hugovk]

For reference, the suggested convention is at https://devguide.python.org/documentation/markup/#sections

Normally, there are no heading levels assigned to certain characters as the structure is determined from the succession of headings. However, for the Python documentation, here is a suggested convention:

• # with overline, for parts
• * with overline, for chapters
• =, for sections
• -, for subsections
• ^, for subsubsections
• ", for paragraphs

For this file, are we starting at =, then - and ^?

[erlend-aasland]

For this file, are we starting at =, then - and ^?

For which file?

[ezio-melotti]

For which file?

This PR updates the headings of 8 files and, if the update follows the convention described above, then it can be approved and merged. If the other files already follow this convention, then there is nothing else to do.
If they don't, we might as well update all other files while we are at it, either in this PR or, if it turns out to be a major endeavor, we can also do it in batches.

[erlend-aasland]

This PR updates all files in the devguide to follow the convention described in the style guide. Does that answer your question, @ezio-melotti?

[AlexWaygood]

LGTM other than https://github.com/python/devguide/pull/1239/files#r1417581480

[hugovk]

For this file, are we starting at =, then - and ^?

For which file?

I obviously didn't scroll very far down the diff! 😅

Let's try again:

For these files, are we starting at =, then - and ^?

When would we use the overlines?

• # with overline, for parts
• * with overline, for chapters

If a page wants more than four levels? In that case, it would be a bit of a tricky refactor, and it's probably a good idea to avoid such deep nesting.

[erlend-aasland]

For these files, are we starting at =, then - and ^?

Starting at = it appears.

[erlend-aasland]

Thanks for the reviews! I'll land this post house chores 🏠🗑️