Replace List[X] with list[X] in docs

[NickCrews]

As well as Dict[X, Y] -> dic[X, Y], etc.

This is a follow-up to #11377, where
just a single page of the docs was transitioned.
I did a grep through the docs/ directory for anything
matching "List[", "Dict[", "Tuple[", and "Set["
and corrected any examples. Perhaps I missed something, but
my goal was to clean all of the docs.

I tried to strike a balance of how explicit to be: In places related
to collections, such as the "Explicit types for collections" section
of type_inference_and_annotations.rst, I kept
in notes about the differences
between List and list. But in most examples
that were focused
on some other topic, I just deleted any reference to
typing.List. I thought any notes there would
just add noise.

There also is a correction to command_line.rst, I tested using
--disallow-any-generics with list[int] and it works fine.

There are a few typos and style fixes scattered throughout as well when
I touched them.

Test Plan

CI looks like it passed.

[NickCrews]

Uh oh @hauntsaninja, by reviewing #11377 it looks like you have made yourself vulnerable to being a reviewer for this, too!

[hauntsaninja]

Thanks! I walked back a little of the change to the cheat sheet... we get some users who are very new to Python, so it's worth trying to shield them from some of the details.

[NickCrews]

Thanks a lot @hauntsaninja! It's really nice to contribute and for those contributions to land so quickly. I appreciate the work you're doing!