doc: add the note about 'data' event

Refs #2691.

doc/api/http.markdown

@@ -128,7 +128,8 @@ See [net.Server.close()](net.html#server.close).
 This object is created internally by a HTTP server -- not by
 the user -- and passed as the first argument to a `'request'` listener.
 
-This is an `EventEmitter` with the following events:
+The request implements the [Readable Stream](streams.html#readable_Stream)
+interface. This is an `EventEmitter` with the following events:
 
 ### Event: 'data'
 
@@ -141,6 +142,9 @@ argument. The transfer-encoding has been decoded.  The
 body chunk is a string.  The body encoding is set with
 `request.setEncoding()`.
 
+Note that the __data will be lost__ if there is no listener when a
+`ServerRequest` emits a `'data'` event.
+
 ### Event: 'end'
 
 `function () { }`
@@ -245,7 +249,10 @@ authentication details.
 ## http.ServerResponse
 
 This object is created internally by a HTTP server--not by the user. It is
-passed as the second parameter to the `'request'` event. It is a `Writable Stream`.
+passed as the second parameter to the `'request'` event.
+
+The response implements the [Writable  Stream](streams.html#writable_Stream)
+interface. This is an `EventEmitter` with the following events:
 
 ### Event: 'close'
 
@@ -575,11 +582,11 @@ event, the entire body will be caught.
       }, 10);
     });
 
-This is a `Writable Stream`.
 Note: Node does not check whether Content-Length and the length of the body
 which has been transmitted are equal or not.
 
-This is an `EventEmitter` with the following events:
+The request implements the [Writable  Stream](streams.html#writable_Stream)
+interface. This is an `EventEmitter` with the following events:
 
 ### Event 'response'
 
@@ -711,7 +718,9 @@ will be called.
 This object is created when making a request with `http.request()`. It is
 passed to the `'response'` event of the request object.
 
-The response implements the `Readable Stream` interface.
+The response implements the [Readable Stream](streams.html#readable_Stream)
+interface. This is an `EventEmitter` with the following events:
+
 
 ### Event: 'data'
 
@@ -719,6 +728,9 @@ The response implements the `Readable Stream` interface.
 
 Emitted when a piece of the message body is received.
 
+Note that the __data will be lost__ if there is no listener when a
+`ClientResponse` emits a `'data'` event.
+
 
 ### Event: 'end'
 

doc/api/net.markdown

@@ -395,6 +395,9 @@ Emitted when data is received.  The argument `data` will be a `Buffer` or
 (See the [Readable Stream](streams.html#readable_Stream) section for more
 information.)
 
+Note that the __data will be lost__ if there is no listener when a `Socket`
+emits a `'data'` event.
+
 #### Event: 'end'
 
 `function () { }`

doc/api/streams.markdown

@@ -15,6 +15,9 @@ A `Readable Stream` has the following methods, members, and events.
 The `'data'` event emits either a `Buffer` (by default) or a string if
 `setEncoding()` was used.
 
+Note that the __data will be lost__ if there is no listener when a
+`Readable Stream` emits a `'data'` event.
+
 ### Event: 'end'
 
 `function () { }`