Add myself to OWNERS to be able to approve/make infra-related changes

This came up in https://crrev.com/c/758410

R=machenbach@chromium.org

Change-Id: Ia6849a34962628fb17ef61b803f10a1e7c334cd9
Reviewed-on: https://chromium-review.googlesource.com/758852Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49281}

OWNERS

@@ -27,10 +27,11 @@ mstarzinger@chromium.org
 mtrofin@chromium.org
 mvstanton@chromium.org
 mythria@chromium.org
-petermarshall@chromium.org
 neis@chromium.org
+petermarshall@chromium.org
 rmcilroy@chromium.org
 rossberg@chromium.org
+sergiyb@chromium.org
 tebbi@chromium.org
 titzer@chromium.org
 ulan@chromium.org