Add jkrcal@ to components/ntp_snippets/OWNERS

While we're here, also sort the file alphabetically.

Review-Url: https://codereview.chromium.org/2550153002
Cr-Commit-Position: refs/heads/master@{#436304}

components/ntp_snippets/OWNERS

-noyau@chromium.org
+# Main owners:
 bauerb@chromium.org
+jkrcal@chromium.org
 treib@chromium.org
+
+# For ios:
+noyau@chromium.org
+
+# Fallback, in case all of the above are OOO:
 markusheintz@chromium.org