PR submitted, waiting on CLA process.

I added documentation at the field sites, but the audit event table generation does not handle attributes or object.__getattr__ very well at all, so I'm not updating the audit table for now.

The `.. audit-event:: object.__getattr__ obj,name frame-objects` sphinx directive right now just inserts a canned string """Raises an :ref:`auditing event <auditing>` object.__getattr__ with arguments obj,name.""", which would need additional boilerplate to describe these attributes properly. It also only adds a footnote style link to the audit table under __getattr__, and even moves object.__getattribute__ from the first [1] link position to a later number which is IMO is more confusing than not even linking them.

I think to make attributes look good in the table we would need a special sphinx directive for audited object.__getattr__ attributes, for example by modifying the template generator to fit each attribute on its own line under  object.__getattr__ in the table.

For now I did not use the audit-event sphinx directive and manually inserted strings like this near the original attribute description in the docs: """Accessing ``f_code`` raises an :ref:`auditing event <auditing>` ``object.__getattr__`` with arguments ``obj`` and ``"f_code"``."""

I think audit table improvements should be handled in a separate issue, and by someone more familiar with that part of the doc generator, as cleaning it up looks like maybe a bigger scope than the current contribution.