Add default code reviewers into OWNERS

Bug: 33166666
Test: gerrit uploader
Change-Id: Id3c59a59baa3bdebadb42e569e807b4d0a79d955
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..0f0736a
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,2 @@
+nona@google.com
+siyamed@google.com