Add boolean to the style guide

[hugovk]

Fixes python/docs-community#129, which has been open for 11 months with 10 votes in favour of the Google guidance (Ned's comment + 9 👍), and no down votes, and no other suggestions.

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📚 Documentation preview 📚: https://cpython-devguide--1636.org.readthedocs.build/documentation/style-guide/#specific-words

[StanFromIreland]

11 now:-)

[encukou]

By my reading of the Google guidance, this should be:

Suggested change

	Lowercase in most cases.
	Uppercase for Boolean mathematics and Boolean logic.
	Lowercase in most cases.
	Uppercase for *Boolean mathematics* and *Boolean logic*.
	To refer to the Python or C data type, prefer using the exact, abbreviated
	name with appropriate markup (for example, ``:type:`bool```).

[AA-Turner]

To avoid saying "case" twice in one line

Suggested change

	Lowercase in most cases.
	Uppercase for Boolean mathematics and Boolean logic.
	Lowercase in most instances.
	Uppercase for *Boolean mathematics* and *Boolean logic*.
	To refer to the Python or C data type, prefer using the exact,
	abbreviated name with appropriate markup (for example, ``:type:`bool```).

[AA-Turner]

I didn't downvote the comment (that seems too harsh), but I will register support for properly capitalising Boolean as a proper noun. Three of the four style guides quoted say to capitalise, abeit one of them giving the option not to. Google's prefers using the formatting of the type (i.e. bool) where possible, and then diverges from the others in terms of spelling.

I also disagree with the notion that capitalising it is pedantic or distracting, we capitalise other proper nouns properly (e.g. Python, C API). English is a language with lots of capitalisation in places, not just at the start of sentences.

However, if this is the will of the people I won't stand in the way of progress...

A

[willingc]

I approve with adoption of @encukou / @AA-Turner's suggestion.

In general, I think using interchangeably is fine since there is no industry consensus of capitalization.