Missing Full List of MetPy Areas

[kgoebber]

What can be better?

On the following doc page there are only two of the pre-defined areas that are showing on the documentation page, this should be a list of 300 or so areas of associate maps.

https://unidata.github.io/MetPy/latest/api/areas.html

[dopplershift]

At some point we put in a variable to cut down on building all of that when we do local doc builds. I wonder if we lost a config somewhere.