DOC: Unclear how to evaluate using polynomial package

Issue with current documentation:

• The transition guide here does not explain how to transition uses of np.polyval.
• The legacy class documentation here does have an evaluation example, but the actual method that does the work (__call__) has nonsense documentation.
• The class documentation page here doesn't explain how to use the class to evaluate the polynomial, and again __call__ has nonsense documentation.

Idea or request for content:

I would appreciate some more clarity on how to use the newer classes. I was able to figure it out in a REPL but it was not obvious and directly answerable from the docs.