Add Override annotations where appropriate

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

paper-api/src/main/java/org/bukkit/material/Skull.java

@@ -35,6 +35,7 @@ public class Skull extends MaterialData implements Directional {
         super(type, data);
     }
 
+    @Override
     public void setFacingDirection(BlockFace face) {
         int data;
 
@@ -63,6 +64,7 @@ public class Skull extends MaterialData implements Directional {
         setData((byte) data);
     }
 
+    @Override
     public BlockFace getFacing() {
         int data = getData();