add some offline pages members to ntp_snippets/OWNERS

As our team will be maintaining this in the future

Change-Id: I9382de5a7ef6fec6bdb517b12a9d952cf23f38bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1706796Reviewed-by: Nicolas Zea <zea@chromium.org>
Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Commit-Queue: Nicolas Zea <zea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678371}

components/ntp_snippets/OWNERS

 fgorski@chromium.org
 pnoland@chromium.org
+harringtond@chromium.org
+carlosk@chromium.org
+dimich@chromium.org
 zea@chromium.org
 
 # For ios: