Add ExpressInterface to readme

README.md

@@ -70,6 +70,18 @@ func main (){
   app.Start("8080")
 }
 ```
+## ExpressInterface
+You can pass around the instance of ```express``` struct across packages using this interface.
+```go
+func main(){
+  var app = express.Express()
+  attachHandlers(app)
+}
+func attachHandlers(instance express.ExpressInterface){
+  instance.Use(someMiddleware)
+  instance.Set("logging", true)
+}
+```
 ## Cookies
 ```go
 import (

express.go

@@ -22,6 +22,8 @@ type express struct {
 	started bool
 	properties map[string]interface{}
 }
+
+// Public Interface to allow access to express struct's member functions
 type ExpressInterface interface {
 	Use(interface{}) *express
 	Get(string, router.Middleware) *express