Add default code reviewers into OWNERS

Bug: 33166666
Test: gerrit uploader
Change-Id: I922dd2cc290264c28ad5ca77570e21031d40b01b
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..dfd2187
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,4 @@
+# Default code reviewers picked from top 3 or more developers.
+# Please update this list if you find better candidates.
+paulduffin@google.com
+iam@google.com