doc: improve stream documentation

PR-URL: nodejs#18375
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: 陈刚

doc/api/stream.md

@@ -580,8 +580,8 @@ The Readable can switch back to paused mode using one of the following:
 
 * If there are no pipe destinations, by calling the
   [`stream.pause()`][stream-pause] method.
-* If there are pipe destinations, by removing any [`'data'`][] event
-  handlers, and removing all pipe destinations by calling the
+* If there are pipe destinations, by removing all pipe destinations.
+  Multiple pipe destinations may be removed by calling the
   [`stream.unpipe()`][] method.
 
 The important concept to remember is that a Readable will not generate data
@@ -1459,7 +1459,7 @@ write succeeded.
 
 All calls to `writable.write()` that occur between the time `writable._write()`
 is called and the `callback` is called will cause the written data to be
-buffered. Once the `callback` is invoked, the stream will emit a [`'drain'`][]
+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.