added script to generate release notes

scripts/release-notes.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env sh
+
+RELEASE=${1:-${GIT_TAG}}
+RELEASE=${RELEASE:-${CIRCLE_TAG}}
+
+if [ -z "${RELEASE}" ]; then
+	echo "Usage:"
+	echo "release-notes.sh VERSION"
+	exit 1
+fi
+
+if ! git rev-list ${RELEASE} >/dev/null 2>&1; then
+	echo "${RELEASE} does not exist"
+	exit
+fi
+
+REPO="knative-lambda-runtime"
+BASE_URL="https://github.com/triggermesh/${REPO}/releases/download/${RELEASE}"
+PREV_RELEASE=${PREV_RELEASE:-$(git describe --tags --abbrev=0 ${RELEASE}^ 2>/dev/null)}
+PREV_RELEASE=${PREV_RELEASE:-$(git rev-list --max-parents=0 ${RELEASE}^ 2>/dev/null)}
+NOTABLE_CHANGES=$(git cat-file -p ${RELEASE} | sed '/-----BEGIN PGP SIGNATURE-----/,//d' | tail -n +6)
+CHANGELOG=$(git log --no-merges --pretty=format:'- [%h] %s (%aN)' ${PREV_RELEASE}..${RELEASE})
+if [ $? -ne 0 ]; then
+	echo "Error creating changelog"
+	exit 1
+fi
+
+RUNTIMES=$(sed -n -e "s/^\(RUNTIMES[[:space:]]*=[[:space:]]*\)\(.*\)$/\2/p" Makefile)
+RELEASE_ASSETS_TABLE=$(
+  echo -n "|"; for runtime in ${RUNTIMES}; do echo -n " ${runtime} |"; done ; echo
+  echo -n "|"; for runtime in ${RUNTIMES}; do echo -n "--|"; done ; echo
+  echo -n "|"
+  for runtime in ${RUNTIMES}; do
+    echo -n " [container](https://gcr.io/triggermesh/knative-lambda-$(echo "${runtime}" | sed -n -e "s/\([[:alnum:]]*\)\(-\)*\([0-9]*\)\(\.\)*\([0-9]*\)\(\.\)*\([0-9]*\).*/\1\3\5\7/p"):${RELEASE})"
+    echo -n " |"
+  done
+  echo
+)
+
+cat <<EOF
+${NOTABLE_CHANGES}
+
+## Installation
+
+Download TriggerMesh Knative Lambda Runtime ${RELEASE}
+
+${RELEASE_ASSETS_TABLE}
+
+## Changelog
+
+${CHANGELOG}
+EOF