[mate-panel] add explanation for mate-session-manager requirement

[leigh123linux]

commit c5a3f5965ba52f913c2ac9036f88b8aeaf0fa361
Author: leigh123linux <leigh123linux at googlemail.com>
Date:   Mon Oct 22 18:05:53 2012 +0100

    add explanation for mate-session-manager requirement

 mate-panel.spec |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/mate-panel.spec b/mate-panel.spec
index 2e52ff0..64064ea 100644
--- a/mate-panel.spec
+++ b/mate-panel.spec
@@ -41,6 +41,7 @@ Requires(pre):  mate-conf
 Requires(post): mate-conf
 Requires(preun): mate-conf
 
+# needed as nothing else requires it
 Requires: mate-session-manager
 
 #for fish