fix: fix typo in subject_priority_policy.csv (#425)

Author: diipanshuu

examples/subject_priority_policy.csv

@@ -2,7 +2,7 @@ p, root, data1, read, deny
 p, admin, data1, read, deny
 
 p, editor, data1, read, deny
-p, subscriber, data1, deny
+p, subscriber, data1, read, deny
 
 p, jane, data1, read, allow
 p, alice, data1, read, allow