[API] Generator: run rubocop when updating api source code

Author: picandocodigo

elasticsearch-api/utils/update_files.sh

@@ -1,2 +1,5 @@
 #!/bin/sh
+echo "Copying generated files into lib..."
 cp ../tmp/out/api/* ../lib/elasticsearch/api/actions/ -R
+echo "Running Rubocop..."
+rubocop -x ../lib/elasticsearch/api/actions