Switch array-like (M, N) to (M, N) array-like.

[anntzer]

Also use "array" instead of "array-like" for return types if
appropriate. Some instances were left unchanged as they may need more
editing anyways.

See discussion at #16161 (comment).

PR Summary

PR Checklist

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (run flake8 on changed files to check).
• New features are documented, with examples if plot related.
• Documentation is sphinx and numpydoc compliant (the docs should build without error).
• Conforms to Matplotlib style conventions (install flake8-docstrings and run flake8 --docstring-convention=all).
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).

[timhoffm]

Suggested change

	y : 2D (M, N) array or sequence of (N,) array-like
	y : (M, N) array-like

• 2D not needed if we have (M, N)
• Doesn't (M, N) array-like include sequence of (N,) array-like?

[anntzer]

yes (twice)