Set category to undefined

Author: michalsnik

lib/rules/prop-name-casing.js

@@ -59,7 +59,7 @@ module.exports = {
   meta: {
     docs: {
       description: 'enforce specific casing for the Prop name in Vue components',
-      category: 'upcoming' // 'strongly-recommended'
+      category: undefined // 'strongly-recommended'
     },
     fixable: null,  // or "code" or "whitespace"
     schema: [