doc: generalize the note after rewiew suggestions

Author: prog1dev

doc/api/stream.md

@@ -1198,9 +1198,10 @@ print(fs.createReadStream('file')).catch(console.log);
 If the loop terminates with a `break` or a `throw`, the stream will be
 destroyed. In other terms, iterating over a stream will consume the stream
 fully. 
-Note that by default, async reading of the contents of the file will be
-performed by chunks of size equal to `highWaterMark` value (default is 64kb
-for [`fs.createReadStream()`][]).
+The stream will be read in chunks of size equal to the `highWaterMark` option.
+In the code example above, data will be in a single chunk if the file has less
+then 64kb of data because no `highWaterMark` option is provided to
+[`fs.createReadStream()`][].
 
 ### Duplex and Transform Streams