message: creature: fix typo
  Thanks Ariel.
diff: @@ -277,7 +277,7 @@ void NWNX_Creature_LevelUp(object creature, int class, int count=1);
  // This will not work on player characters
  void NWNX_Creature_LevelDown(object creature, int count=1);
  -// Sets corpse decay time in milliseconds
  +// Sets the creature's challenge rating
  void NWNX_Creature_SetChallengeRating(object creature, float fCR);
  // Returns the creature's highest attack bonus based on its own stats
  