Include notes for nginx as well

README.md

@@ -65,7 +65,10 @@ Digest authentication example
 WSGI Considerations
 -------------------
 
-Make sure to set `WSGIPassAuthorization On` as [documented here](https://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIPassAuthorization) to prevent the frontend web server from consuming the authorization header.
+Make sure that the authorization headers are passed through to your application.  Otherwise, your callbacks will have empty values for the user & password.  Here are the directives needed for the following web servers.
+
+- Apache: set `WSGIPassAuthorization On` as [documented here](https://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIPassAuthorization).
+- Nginx: set `wsgi_pass_authorization on` as [documented here](http://wiki.nginx.org/NgxWSGIModule)
 
 Resources
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