feat: Update

- Event for GroupDM
- Friend nickname
#29

src/structures/User.js

@@ -196,6 +196,15 @@ class User extends Base {
     return this.client.user.notes.get(this.id);
   }
 
+  /**
+   * Get friend nickname
+   * @type {?string}
+   * @readonly
+   */
+  get nickname() {
+    return this.client.user.friendNicknames.get(this.id);
+  }
+
   /**
    * The voice state of this member
    * @type {VoiceState}
@@ -282,6 +291,16 @@ class User extends Base {
     return this.client.relationships.addFriend(this);
   }
 
+  /**
+   * Changes the nickname of the friend
+   * @param {?string} nickname The nickname to change
+   * @type {boolean}
+   * @returns {Promise<boolean>}
+   */
+  setNickname(nickname) {
+    return this.client.user.setNickname(this.id, nickname);
+  }
+
   /**
    * Send Friend Request to the user
    * @type {boolean}