[openstack-packstack/el6-grizzly] doc: mention why we install the RDO release RPM

[Pádraig Brady]

commit 923ddbb3421c54dc5a26b180921fa31fd2ebca73
Author: Pádraig Brady <P at draigBrady.com>
Date:   Mon Jul 15 13:55:14 2013 +0100

    doc: mention why we install the RDO release RPM

 enable-epel-and-el6-grizzly.patch |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/enable-epel-and-el6-grizzly.patch b/enable-epel-and-el6-grizzly.patch
index 64d35ac..0fccf5d 100644
--- a/enable-epel-and-el6-grizzly.patch
+++ b/enable-epel-and-el6-grizzly.patch
@@ -1,3 +1,8 @@
+RDO requires EPEL, so enable that.
+
+Also install the RDO release rpm, so that it's present on all hosts,
+not just the host that packstack was initiated on.
+
 diff -ru packstack-2013.1.1dev538.orig/packstack/plugins/serverprep_901.py packstack-2013.1.1dev538/packstack/plugins/serverprep_901.py
 --- packstack-2013.1.1dev538.orig/packstack/plugins/serverprep_901.py	2013-04-09 04:47:16.000000000 -0700
 +++ packstack-2013.1.1dev538/packstack/plugins/serverprep_901.py	2013-04-14 17:30:53.044132006 -0700