doc: fix quotes in stream docs

PR-URL: #37269
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/stream.md

@@ -2029,7 +2029,7 @@ user programs.
     be written. The `chunk` will be a string if the `Writable` was created with
     the `decodeStrings` option set to `false` and a string was passed to `write()`.
   * `encoding` {string} The character encoding of the `chunk`. If `chunk` is
-    a `Buffer`, the `encoding` will be `'buffer`.
+    a `Buffer`, the `encoding` will be `'buffer'`.
 * `callback` {Function} A callback function (optionally with an error
   argument) to be invoked when processing is complete for the supplied chunks.