PushPermissionsIT: add hint about addPatchSetDenied 

Change-Id: I6ccc0a6c518a8f87d103499e6153a98cc331f0c2
diff --git a/javatests/com/google/gerrit/acceptance/git/PushPermissionsIT.java b/javatests/com/google/gerrit/acceptance/git/PushPermissionsIT.java
index 66af8a4..0ae99b0 100644
--- a/javatests/com/google/gerrit/acceptance/git/PushPermissionsIT.java
+++ b/javatests/com/google/gerrit/acceptance/git/PushPermissionsIT.java
@@ -284,6 +284,7 @@
     ObjectId ps1Id = forceFetch(PatchSet.id(id, 1).toRefName());
     ObjectId ps2Id = testRepo.amend(ps1Id).add("file", "content").create();
     PushResult r = push(ps2Id.name() + ":refs/for/master");
+    // Admin had ADD_PATCH_SET removed in setup.
     assertThat(r)
         .onlyRef("refs/for/master")
         .isRejected("cannot add patch set to " + id.get() + ".");