Update FaweVersion.java (#728)

worldedit-core/src/main/java/com/boydti/fawe/FaweVersion.java

@@ -1,5 +1,6 @@
 package com.boydti.fawe;
 
+/** An internal FAWE class not mean't for public use. **/
 public class FaweVersion {
     public final int year;
     public final int month;