Add helper script to run gen script

hack/gen.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+if [ "$(git branch --show-current)" != "master" ]; then
+    echo "Not in master branch. Aborting."
+    exit 1
+fi
+
+BRANCH_NAME="update-gh-definitions-$(date '+%s')"
+
+git checkout -b ${BRANCH_NAME}
+
+go run main.go
+
+if [ "$(git status --porcelain | wc -l)" != "1" ]; then
+    echo "Found more changes than expected. Aborting."
+    exit 1
+fi
+
+git commit -am "Update GH definitions"
+
+git push origin ${BRANCH_NAME}