Make arc-owners actually own arc/*.

BUG=448059
diff --git a/project.config b/project.config
index 8fc4818..298427a 100644
--- a/project.config
+++ b/project.config
@@ -8,6 +8,7 @@
 	read = group Anonymous Users
 [access "refs/*"]
 	owner = group Administrators
+	owner = group arc-owners
 	read = group arc-committers
 	read = group arc-owners
 [access "refs/for/refs/*"]