Update on "Add script to cut release branch"

Step 1 of release process: Create a release branch.

The branch is named with `release/MAJOR.MINOR`.

From executorch root, run `./scripts/release/cut-release-branch.sh` will cut a release branch off stable branch (`viable/strict`) by default. Use `GIT_BRANCH_TO_CUT_FROM=main ./scripts/release/cut-release-branch.sh` to cut off `main` branch.



Differential Revision: [D55208762](https://our.internmc.facebook.com/intern/diff/D55208762)

[ghstack-poisoned]

Author: guangy10

scripts/release/cut-release-branch.sh

@@ -1,4 +1,9 @@
 #!/usr/bin/env bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
 
 : '
 So you are looking to cut a release branch? Well you came