Add mammoth to map descriptions.

Author: dsvensson

data/map.metadata.json

@@ -269,5 +269,9 @@
     "qwq3wcp9": {
         "name": "Spider Crossings",
         "author": "3w"
-    }
-}
+    },
+	"mammoth": {
+		"name": "Mammoth Depot",
+		"author": "alice"
+	}
+}