doc: revert incorrect change on readable._read

nodejs#17979 introduced a change in the
doc that was not correct about _read always being called asynchronously.
This does not hold true when it is in flowing mode.

See: nodejs#17979
Fixes: nodejs#24919

PR-URL: nodejs#25442
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>

doc/api/stream.md

@@ -1858,10 +1858,6 @@ const myReadable = new Readable({
 #### readable.\_read(size)
 <!-- YAML
 added: v0.9.4
-changes:
-  - version: v10.0.0
-    pr-url: https://github.com/nodejs/node/pull/17979
-    description: Call `_read()` only once per microtick.
 -->
 
 * `size` {number} Number of bytes to read asynchronously
@@ -1881,9 +1877,7 @@ when `_read()` is called again after it has stopped should it resume pushing
 additional data onto the queue.
 
 Once the `readable._read()` method has been called, it will not be called again
-until the [`readable.push()`][stream-push] method is called. `readable._read()`
-is guaranteed to be called only once within a synchronous execution, i.e. a
-microtick.
+until the [`readable.push()`][stream-push] method is called.
 
 The `size` argument is advisory. For implementations where a "read" is a
 single operation that returns data can use the `size` argument to determine how