Fix End Stone name (#3578)

src/main/resources/experience.yml

@@ -196,7 +196,7 @@ Experience:
         Emerald_Ore: 1000
         End_Bricks: 200
         Nether_Brick: 50
-        Ender_Stone: 150
+        End_Stone: 150
         Glowstone: 30
         Gold_Ore: 350
         Hard_Clay: 30