Updated metadata (#162)

Author: mattscepter

lib/rules/heading-order.json

@@ -12,7 +12,7 @@
   ],
   "metadata": {
     "description": "Ensures the order of headings is semantically correct",
-    "help": "Heading levels must increase by one"
+    "help": "Heading levels must only increase by one"
   },
   "all": [],
   "any": ["heading-order"],