Update README.md

Add some troubleshooting to handle known issue with Webpack

fixes #657 
fixes #663

README.md

@@ -127,6 +127,23 @@ management
 
 The types for this library are currently maintained by the community at [Definitely Typed](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/auth0). The team is planning taking ownership of this library as discussed in https://github.com/auth0/node-auth0/issues/572. After the team has taken ownership we will remove this net from the Readme.
 
+## Troubleshooting
+
+### Getting `Error: Can't resolve 'superagent-proxy'` when bundling with Webpack
+
+We have a dependency on `rest-facade` which `require`s but doesn't include `superagent-proxy`. This SDK doesn't support proxies, so this dependency is not required. To workaround this you can add the following to your `webpack.config.js`:
+
+```
+resolve: {
+  alias: {
+    'superagent-proxy': false
+  }
+}
+```
+
+Or install `superagent-proxy` yourself.
+
+
 ## What is Auth0?
 
 Auth0 helps you to: