doc: fix documentation for fs.createWriteStream highWaterMark option

PR-URL: nodejs#49456
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: LiviaMedeiros <livia@cirno.name>

Author: mertcanaltin

doc/api/fs.md

@@ -325,6 +325,7 @@ added: v16.11.0
   * `autoClose` {boolean} **Default:** `true`
   * `emitClose` {boolean} **Default:** `true`
   * `start` {integer}
+  * `highWaterMark` {number} **Default:** `16384`
 * Returns: {fs.WriteStream}
 
 `options` may also include a `start` option to allow writing data at some
@@ -2563,6 +2564,7 @@ changes:
   * `start` {integer}
   * `fs` {Object|null} **Default:** `null`
   * `signal` {AbortSignal|null} **Default:** `null`
+  * `highWaterMark` {number} **Default:** `16384`
 * Returns: {fs.WriteStream}
 
 `options` may also include a `start` option to allow writing data at some