Pattern 10 (Callback Documentation Convention) now owns the full rule
for callback documentation — both the behaviour side (@callback docs)
and the implementation side (when to override @doc false on @impl
functions). Patterns 2 and 5 cross-reference Pattern 10 instead of
making their own partial statements.
The test: "Would this statement be true of any implementation?" If yes,
it belongs on the @callback. If no, the implementation earns its own
@doc.
aweiker