Add script for updating prod tag (#1473)

This is currently available for copy/paste from release documentation
but does not take into account that remote names vary.

scripts/update_prod_tag.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Updates the prod tag to point to the latest semantically versioned release.
+
+set -e
+set -o pipefail
+
+# Find the remote associated with the main repo
+upstream_remote=$(git remote -v | grep "datacommonsorg" | cut -f1 | uniq)
+if [ -z "$upstream_remote" ]; then
+  echo "No remote found with 'datacommonsorg' in its URL."
+  exit 1
+fi
+echo "Remote for main repo is '${upstream_remote}'".
+
+# Check out the latest release tag
+# The latest tag will start with the letter "v", example "v2.0.12".
+# sort -V uses "version" sorting to get the latest tag
+git fetch "$upstream_remote" --tags
+latest_release_tag=$(git tag -l "v*" | sort -V | tail -n1)
+git checkout "$latest_release_tag"
+
+# Confirm before updating the tag
+read -r -p "Update the mixer prod tag to point to '$latest_release_tag'? [y/n] " response
+if [[ ! "$response" =~ ^[Yy]$ ]]; then
+  echo "Aborting..."
+  exit 0
+fi
+
+# Delete the old prod tag locally and remotely
+git tag -d prod
+git push "$upstream_remote" :refs/tags/prod
+
+# Tag release as prod & push to github
+git tag prod
+git push "$upstream_remote" prod