Makefile target to avoid re adding it by mistake (#38)

Signed-off-by: Friedrich Gonzalez <friedrichg@gmail.com>

Author: friedrichg

Makefile

@@ -44,3 +44,7 @@ clean:
 		 rm -f cmd/$$app/$$app; \
 	done
 	rm -rf dist
+
+mod-vendor:
+	go mod vendor
+	rm ./vendor/github.com/weaveworks/common/COPYING.LGPL-3