Add performance note to PlayerArgument javadocs

Copied from the documentation for more visibility https://commandapi.jorel.dev/9.5.0/argument_entities.html#player-argument

Author: willkroboth

commandapi-platforms/commandapi-bukkit/commandapi-bukkit-core/src/main/java/dev/jorel/commandapi/arguments/PlayerArgument.java

@@ -27,7 +27,10 @@
 import org.bukkit.entity.Player;
 
 /**
- * An argument that represents the Bukkit Player object
+ * An argument that represents the Bukkit Player object.
+ * <p>
+ * Note that this Argument internally references Mojang's authentication servers to resolve
+ * usernames, which gives it a slight performance overhead compared to {@link EntitySelectorArgument.OnePlayer}.
  * 
  * @since 1.1
  */