docs

docs/guide.md

@@ -39,6 +39,20 @@ app.use(function(next){
 
 ![koa middleware](https://i.cloudup.com/N7L5UakJo0.gif)
 
+ 1. Create a date to track duration
+ 2. Yield control to the next middleware
+ 3. Create another date to track response time
+ 4. Yield control to the next middleware
+ 5. Yield immediately since `contentLength` only works with responses
+ 6. Yield upstream to Koa's noop middleware
+ 7. Ignore setting the body unless the path is "/"
+ 8. Set the response to "Hello World"
+ 9. Ignore setting Content-Length when no body is present
+ 10. Set the field
+ 11. Output log line
+ 12. Set `X-Response-Time` header field before response
+ 13. Hand off to Koa to handle the response
+
   Next we'll look at the best practices for creating Koa middleware.
 
 ## Middleware Best Practices