Updating documentation with detail on how to add and use custom Expre…

…ss middleware, currently undocumented

config.express.md

@@ -0,0 +1,19 @@
+# Express
+This configuration file lets you easily add [Express](http://expressjs.com/) middleware, local variables and helpers for templates and directly access the application instance before it starts. 
+
+```javascript
+module.exports.express = {
+
+  customMiddleware: false
+
+  /*
+  // Say you want to use `connect-flash` for messaging within a session 
+  customMiddleware: function (app) {
+    var flash = require('connect-flash');
+    app.use(flash());
+  }
+  
+  */
+
+};
+```

config.md

@@ -19,6 +19,9 @@
 ####[CSRF](https://github.com/balderdashy/sails-wiki/blob/0.9/config.csrf.md)
 >When enabled, all non-GET requests to the Sails server must be accompanied by a special token, identified as the '_csrf' parameter.
 
+####[Express](https://github.com/balderdashy/sails-wiki/blob/0.9/config.express.md)
+>If you want to use custom middleware or add local variables and helpers to templates you can do so by configuring express in this config file.
+
 ####[Local](https://github.com/balderdashy/sails-wiki/blob/0.9/config.local.md)
 >While you’re developing your app, this config file should include any settings specifically for your development computer (db passwords, etc.)