Correct annotation for render events

[tschaub]

This updates the @fires annotation for a few layers. Previously, the docs made it look like these layers fired the rendercomplete event. After this change, the docs show that they fire prerender and postrender events instead.

Thanks @ahocevar for pointing out the fix (see #16300 (comment)).

[ahocevar]

Thanks for fixing this, @tschaub!