ART: Add OWNERS file

Add TLMs as explicit owners. Give everyone else owner capabilities,
too.

Test: none
Change-Id: I0b84ef01423045a54928b8ef497eda69240a2abe
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..7297a14
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,3 @@
+ngeoffray@google.com
+sehr@google.com
+*