Correct method default in docstring

[chrishalcrow]

Fixes #3566

Correct the default method docstring in compute_unit_locations. Was center_of_mass but monopolar_triangulation is actually the default.

[zm711]

why or instead of |? We had decided on doing | in general, but have never enforced it. Do you want to make an argument for using or instead. The | in type hints is 3.10+, but in docstrings there are no rules.

[chrishalcrow]

why or instead of |? We had decided on doing | in general, but have never enforced it. Do you want to make an argument for using or instead. The | in type hints is 3.10+, but in docstrings there are no rules.

Oh, crud. Yes indeed, that's in our docstring conventions - my mistake!

[zm711]

good by me.