[Autofill Assistant] Updated owners file for autofill assistant.

Bug: 806868
Change-Id: I7d39618f9a51680f9de3b747192f93cc4667de08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776035
Auto-Submit: Clemens Arbesser <arbesser@google.com>
Reviewed-by: Jordan Demeulenaere <jdemeulenaere@chromium.org>
Commit-Queue: Jordan Demeulenaere <jdemeulenaere@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692017}

components/autofill_assistant/OWNERS

@@ -2,6 +2,7 @@
 arbesser@google.com
 gogerald@chromium.org
 jdemeulenaere@chromium.org
+marianfe@google.com
 mcarlen@chromium.org
 rouslan@chromium.org
 szermatt@chromium.org