SPIGOT-2659: Better JavaDoc for setCanPickupItems

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/entity/LivingEntity.java

@@ -338,6 +338,8 @@ public interface LivingEntity extends Attributable, Entity, Damageable, Projecti
 
     /**
      * Sets whether or not the living entity can pick up items.
+     * <p>
+     * This method has no effect on a {@link HumanEntity}.
      *
      * @param pickup whether or not the living entity can pick up items
      */