message: Update `bin/bitgo-express` command in README
diff: @@ -84,7 +84,7 @@ Suitable for developers working in a language without an official BitGo SDK.
  BitGo Express runs as a service in your own datacenter, and handles the client-side operations involving your own keys, such as partially signing transactions before submitting to BitGo.
  This ensures your keys never leave your network, and are not seen by BitGo. BitGo Express can also proxy the standard BitGo REST APIs, providing a unified interface to BitGo through a single REST API.
  -`bin/bitgo-express [-h] [-v] [-p PORT] [-b BIND] [-e ENV] [-d] [-l LOGFILEPATH] [-k KEYPATH] [-c CRTPATH]`
  +`npm explore bitgo -- bin/bitgo-express [-h] [-v] [-p PORT] [-b BIND] [-e ENV] [-d] [-l LOGFILEPATH] [-k KEYPATH] [-c CRTPATH]`
  **Note:** When running against the BitGo production environment, you must run node in a production configuration as well. You can do that by running `export NODE_ENV=production` prior to starting bitgo-express.
  