doc: fix typo in webstreams.md

PR-URL: https://github.com/nodejs/node/pull/50426
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/webstreams.md

@@ -206,7 +206,7 @@ added: v16.5.0
 * `transform` {Object}
   * `readable` {ReadableStream} The `ReadableStream` to which
     `transform.writable` will push the potentially modified data
-    is receives from this `ReadableStream`.
+    it receives from this `ReadableStream`.
   * `writable` {WritableStream} The `WritableStream` to which this
     `ReadableStream`'s data will be written.
 * `options` {Object}