[ios] Silence undocumented typedef warnings from appledoc

ref #3203

Author: 1ec5

include/mbgl/ios/MGLMapView+MGLCustomStyleLayerAdditions.h

@@ -2,15 +2,18 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+/// -
 typedef void (^MGLCustomStyleLayerPreparationHandler)(void);
 
+/// -
 typedef void (^MGLCustomStyleLayerDrawingHandler)(CGSize size,
                                                   CLLocationCoordinate2D centerCoordinate,
                                                   double zoomLevel,
                                                   CLLocationDirection direction,
                                                   CGFloat pitch,
                                                   CGFloat perspectiveSkew);
 
+/// -
 typedef void (^MGLCustomStyleLayerCompletionHandler)(void);
 
 @interface MGLMapView (MGLCustomStyleLayerAdditions)