docs(MessageManager): document return type of delete (#4012)

* docs(MessageManager): document return type of delete

* docs(MessageManager): use Promise<void> over Promise

Co-Authored-By: Papaia <43409674+ItsPapaia@users.noreply.github.com>

Co-authored-by: Papaia <43409674+ItsPapaia@users.noreply.github.com>

src/managers/MessageManager.js

@@ -115,6 +115,7 @@ class MessageManager extends BaseManager {
    * Deletes a message, even if it's not cached.
    * @param {MessageResolvable} message The message to delete
    * @param {string} [reason] Reason for deleting this message, if it does not belong to the client user
+   * @returns {Promise<void>}
    */
   async delete(message, reason) {
     message = this.resolveID(message);