doc: fix about decodeStrings property of stream.Writable

doc/api/stream.md

@@ -1500,13 +1500,11 @@ buffered. When the `callback` is invoked, the stream might emit a [`'drain'`][]
 event. If a stream implementation is capable of processing multiple chunks of
 data at once, the `writable._writev()` method should be implemented.
 
-If the `decodeStrings` property is set in the constructor options, then
-`chunk` may be a string rather than a Buffer, and `encoding` will
-indicate the character encoding of the string. This is to support
-implementations that have an optimized handling for certain string
-data encodings. If the `decodeStrings` property is explicitly set to `false`,
-the `encoding` argument can be safely ignored, and `chunk` will remain the same
-object that is passed to `.write()`.
+If the `decodeStrings` property is explicitly set to `false` in the constructor
+options, then `chunk` will remain the same object that is passed to `.write()`,
+and may be a string rather than a Buffer. In that case, the `encoding` argument
+will indicate the character encoding of the string. Otherwise, the `encoding`
+argument can be safely ignored.
 
 The `writable._write()` method is prefixed with an underscore because it is
 internal to the class that defines it, and should never be called directly by