SWIFT-937 Add a release script (#42)

Author: kmahar

etc/release.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# usage: ./etc/release.sh [new version string]
+
+# exit if any command fails
+set -e
+
+# ensure we are on master before releasing
+git checkout master
+
+version=${1}
+# Ensure version is non-empty
+[ ! -z "${version}" ] || { echo "ERROR: Missing version string"; exit 1; }
+
+# regenerate documentation with new version string
+./etc/generate-docs.sh ${version}
+
+# tag release and push tag
+git tag "v${version}"
+git push --tags
+
+# go to GitHub to publish release notes
+open "https://github.com/mongodb/swift-bson/releases/tag/v${version}"