fix(Guild): fix vanityURLUses desc, internally use fetchVanityData (#4335)

* docs(vanityURLUses): use fetchVanityData

* feat(fetchVanityCode): internally call fetchVanityData

* Update src/structures/Guild.js

Author: papaia

src/structures/Guild.js

@@ -336,7 +336,7 @@ class Guild extends Base {
     /* eslint-disable max-len */
     /**
      * The use count of the vanity URL code of the guild, if any
-     * <info>You will need to fetch the guild using {@link Guild#fetchVanityCode} if you want to receive this parameter</info>
+     * <info>You will need to fetch this parameter using {@link Guild#fetchVanityData} if you want to receive it</info>
      * @type {?number}
      */
     this.vanityURLUses = null;
@@ -771,13 +771,7 @@ class Guild extends Base {
    *   .catch(console.error);
    */
   fetchVanityCode() {
-    if (!this.features.includes('VANITY_URL')) {
-      return Promise.reject(new Error('VANITY_URL'));
-    }
-    return this.client.api
-      .guilds(this.id, 'vanity-url')
-      .get()
-      .then(res => res.code);
+    return this.fetchVanityData().then(vanity => vanity.code);
   }
 
   /**