[ios, macos] Removed inaccurate MGLOverlay commentary

This paragraph is full of references to features that exist in MKOverlay but not MGLOverlay.

platform/darwin/src/MGLOverlay.h

@@ -17,14 +17,6 @@ NS_ASSUME_NONNULL_BEGIN
  example, you could use an overlay to show the boundaries of a national park or
  trace a bus route along city streets. This SDK defines several concrete classes
  that conform to this protocol and define standard shapes.
- 
- Because overlays are also annotations, they have similar usage pattern to
- annotations. When added to a map view using the `-addOverlay:` method, that
- view detects whenever the overlay’s defined region intersects the visible
- portion of the map. At that point, the map view asks its delegate to provide a
- special overlay view to draw the visual representation of the overlay. If you
- add an overlay to a map view as an annotation instead, it is treated as an
- annotation with a single point.
  */
 @protocol MGLOverlay <MGLAnnotation>