Here as well probably put a code snippet show how to import and inherit from a plugin interface. Sorry I know I've gone back-and-forth about this, opinions about docs guidelines are still being formed, but I'm starting to think that small snippets showing how to do something improve clarity, once they become complete classes or functions that are meant to work then they should be in a separate file and have unit tests.

Also, when mentioning plugin interfaces here I think it's worth a cross-ref to the plugin interfaces reference section below.