add comment about npm executable

bin/compile

@@ -44,7 +44,7 @@ status "Downloading and installing node"
 node_url="http://s3pository.heroku.com/node/v$node_version/node-v$node_version-linux-x64.tar.gz"
 curl $node_url -s -o - | tar xzf - -C $build_dir
 
-# Move node into ./vendor and make it executable
+# Move node (and npm) into ./vendor and make them executable
 mkdir -p $build_dir/vendor
 mv $build_dir/node-v$node_version-linux-x64 $build_dir/vendor/node
 chmod +x $build_dir/vendor/node/bin/*