update document

docs/api/request.md

@@ -307,3 +307,19 @@ this.acceptsLanguages();
 // => ["es", "pt", "en"]
 ```
 
+### req.idempotent
+
+  Check if the request is idempotent.
+
+### req.socket
+
+  Return the request socket.
+
+### req.vary(field)
+
+  Vary on `field`.
+  
+### req.get(field)
+
+  Return request header.
+

docs/api/response.md

@@ -10,10 +10,18 @@
 
   Response header object.
 
+### res.socket
+  
+  Request socket.
+
 ### res.status
 
   Get response status. By default, `res.status` is not set unlike node's `res.statusCode` which defaults to `200`.
 
+### res.statusString
+
+  Response status string
+
 ### res.status=
 
   Set response status via numeric code or case-insensitive string:
@@ -243,3 +251,13 @@ this.response.lastModified = new Date();
 ```js
 this.response.etag = crypto.createHash('md5').update(this.body).digest('hex');
 ```
+
+### res.append(field, val)
+
+  Append `val` to header `field`.
+
+### res.vary(field)
+  
+  Vary on `field`.
+
+