Fix Mycelium name (#3579)

src/main/resources/experience.yml

@@ -133,7 +133,7 @@ Experience:
         Podzol: 40
         Grass_Block: 40
         Gravel: 40
-        Mycel: 40
+        Mycelium: 40
         Sand: 40
         Red_Sand: 40
         Snow: 20