Add @dilyevsky to reviewers. (#2094)

* Add @dilyevsky to reviewers.

Per @miekg suggestion on https://github.com/coredns/coredns/pull/2050#pullrequestreview-149538954
adding myself to OWNERS file.

* Also add me into plugin/route53-specific reviewers/approvers.

OWNERS

 reviewers:
   - bradbeam
   - chrisohaver
+  - dilyevsky
   - fastest963
   - fturib
   - greenpau

plugin/route53/OWNERS

 reviewers:
   - yongtang
+  - dilyevsky
 approvers:
   - yongtang
+  - dilyevsky