Document faraway island

include/faraway_island.h

@@ -2,7 +2,7 @@
 #define GUARD_FARAWAY_ISLAND_H
 
 u32 GetMewMoveDirection(void);
-bool8 sub_81D4A58(struct ObjectEvent*);
+bool8 ShouldMewShakeGrass(struct ObjectEvent*);
 void UpdateFarawayIslandStepCounter(void);
 bool8 ObjectEventIsFarawayIslandMew(struct ObjectEvent *);
 bool8 IsMewPlayingHideAndSeek(void);