DOC: conflicting fixed_params type-hint in find_constrained_prior

[wd60622]

Issue with current documentation:

The find_contrained_prior documentation page has "str or float, optional, default None" in the docstring type hint but dict[str, float] in the examples and function signature

Idea or request for content:

Consolidate to the correct type hint. I believe it is dict[str, float]

[ricardoV94]

The docstring about only when there are more than 2 params to optimize also seems wrong. Perhaps something that was true in earlier iterations but is no longer?