update error message on failed connection to use the npm explore npm run chrome cmd

Author: paulirish

lighthouse-cli/index.js

@@ -157,7 +157,8 @@ lighthouse(url, flags, config)
   })
   .catch(err => {
     if (err.code === 'ECONNREFUSED') {
-      console.error('Unable to connect to Chrome. Did you run ./scripts/launch-chrome.sh ?');
+      console.error('Unable to connect to Chrome. Please run Chrome w/ debugging port 9222 open:');
+      console.error('    npm explore -g lighthouse -- npm run chrome');
     } else {
       console.error('Runtime error encountered:', err);
       console.error(err.stack);