Update stream.md - fix issue in setEncoding method

doc/api/stream.md

@@ -911,10 +911,11 @@ added: v0.9.4
 * `encoding` {String} The encoding to use.
 * Returns: `this`
 
-The `readable.setEncoding()` method sets the default character encoding for
-data read from the Readable stream.
+The `readable.setEncoding()` method sets the character encoding for
+data read from the Readable stream. 
 
-Setting an encoding causes the stream data
+By default, no encoding is assigned and stream data will be returned as 
+Buffer objects.  Setting an encoding causes the stream data
 to be returned as string of the specified encoding rather than as `Buffer`
 objects. For instance, calling `readable.setEncoding('utf8')` will cause the
 output data will be interpreted as UTF-8 data, and passed as strings. Calling
@@ -925,10 +926,6 @@ The Readable stream will properly handle multi-byte characters delivered through
 the stream that would otherwise become improperly decoded if simply pulled from
 the stream as `Buffer` objects.
 
-Encoding can be disabled by calling `readable.setEncoding(null)`. This approach
-is useful when working with binary data or with large multi-byte strings spread
-out over multiple chunks.
-
 ```js
 const readable = getReadableStreamSomehow();
 readable.setEncoding('utf8');