Update category

Author: armano2

Diff for: lib/rules/use-v-on-exact.js

@@ -18,7 +18,7 @@ module.exports = {
   meta: {
     docs: {
       description: 'enforce usage of `exact` modifier on `v-on`',
-      category: 'essential',
+      category: undefined, // essential
       url: 'https://github.com/vuejs/eslint-plugin-vue/blob/v5.0.0-beta.3/docs/rules/use-v-on-exact.md'
     },
     fixable: null,