Suggestion: Mention contextlib.ExitStack in "Use backslashes for with statements"?

[joshua-cannon-techlabs]

Is this related to a problem? Please describe.

On Black's future style doc it talks about black handling a with with multiple context managers in a few ways (Python-version-dependent).

Describe the solution you'd like

Black should suggest to the user (in documentation only) that if they don't like Black's current or future behavior, that constructing a contextlib.ExitStack can help the issue while maintaining 95%-ish of the code readability and has minimal overhead.

As an example (feel free to steal), and using the existing code on that page

with contextlib.ExitStack() as exit_stack:
    cm1 = exit_stack.enter_context(make_context_manager(1))
    cm2 = exit_stack.enter_context(make_context_manager(2))
    cm3 = exit_stack.enter_context(make_context_manager(3))
    cm4 = exit_stack.enter_context(make_context_manager(4))
    ...

Describe alternatives you've considered

N/A

Additional context

❤️ black

[joshua-cannon-techlabs]

Related: #2118 #1948