Documentation for Adapter Errors needs improvement

[runspired]

In the overview for adapters we mostly just say to look at the docs for MinimumAdapterInterface, but in the documentation for those methods we do not have more than a spattering of examples for Errors. The documentation for most of the individual AdapterError subclasses is almost entirely non-existent beyond a description, with only InvalidError having any more extensive description.

We should fill this documentation out, and also describe how to return an error that does not extend AdapterError (as extending it is not a requirement). See #7590 for an example of confusion that arises from this missing documentation.