Add creating and committing changelog to Makefile release directive

Makefile

@@ -27,6 +27,9 @@ docs:
 	godoc2md github.com/montanaflynn/stats | sed -e s#src/target/##g > DOCUMENTATION.md
 
 release:
+	git-chglog --next-tag ${TAG} ${TAG} -o CHANGELOG.md
+	git add CHANGELOG.md
+	git commit -m "Update changelog with ${TAG} changes"
 	git tag ${TAG}
 	git-chglog $(TAG) | tail -n +4 | sed '1s/^/$(TAG)\n/gm' > release-notes.txt
 	git push origin master ${TAG}