Adding autosubmit configuration pointer file (flutter#3521)

* Adding autosubmit pointer file

* Forgot to add a space before EOF.

* Updated with link to wiki.

* Addign newline on end of file.

* Remove trailing blank line.

Author: ricardoamador

.github/autosubmit.yml

@@ -0,0 +1,7 @@
+# Copyright 2023 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This file will be added to flutter's internal repository.
+# https://github.com/flutter/flutter/wiki/Autosubmit-bot
+config_path: 'autosubmit/flutter/autosubmit_main.yml'