DOC: Add .map to ExtensionArray reference
Thanks @topper-123  On the docs build here, I'm seeing 

> /home/runner/work/pandas/pandas/doc/source/reference/api/pandas.api.extensions.ExtensionArray.map.rst: WARNING: document isn't included in any toctree

I _think_ this might be causing the docs build to "fail". Oops yeah jumped the gun on the merge. Will revert for now. @datapythonista - in this case the docs are still built successfully but I _think_ we can't use `/preview` because the step is skipped. Is that right? I wonder if there is an easy way still be able to view the docs if something is built (but not a big issue either way). > @datapythonista - in this case the docs are still built successfully but I _think_ we can't use `/preview` because the step is skipped. Is that right? I wonder if there is an easy way still be able to view the docs if something is built (but not a big issue either way).

@rhshadrach we consider warnings as errors in the docs, for me the current behavior seems fine, even if I agree that the docs exist and we could preview them. The main problem I see is that it probably makes the CI quite complex to move forward with the publishing when the docs step is red. But I'm open to the change if things don't become too complicated.

 Thanks @datapythonista - I suspect you're right, but will take a quick look into it to see if anything can be done.