Add Guild#me (#1384)

* Add Guild#me

(also did minor docs cleanup)

* Don't use Guild#member as there's nothing to resolve

* Update ClientDataResolver.js

* Update Guild.js

* Update Guild.js

* Update Guild.js

src/structures/Guild.js

@@ -312,7 +312,7 @@ class Guild {
   }
 
   /**
-   * The `@everyone` Role of the guild
+   * The `@everyone` role of the guild
    * @type {Role}
    * @readonly
    */
@@ -320,6 +320,15 @@ class Guild {
     return this.roles.get(this.id);
   }
 
+  /**
+   * The client user as a GuildMember of this guild
+   * @type {?GuildMember}
+   * @readonly
+   */
+  get me() {
+    return this.members.get(this.client.user.id);
+  }
+
   /**
    * Fetches a collection of roles in the current guild sorted by position
    * @type {Collection<Snowflake, Role>}