[ostree] doc: Note that refs --delete does not prune

[Colin Walters <walters src gnome org>]

commit 2f878afc0292e0817a96569279d6b7cf665b9975
Author: Colin Walters <walters verbum org>
Date:   Mon Sep 28 15:49:12 2015 -0400

    doc: Note that refs --delete does not prune

 doc/ostree-refs.xml |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/doc/ostree-refs.xml b/doc/ostree-refs.xml
index 4a33cd3..e97cb1c 100644
--- a/doc/ostree-refs.xml
+++ b/doc/ostree-refs.xml
@@ -69,7 +69,8 @@ Boston, MA 02111-1307, USA.
                 <term><option>--delete</option></term>
 
                 <listitem><para>
-                    Delete refs which match PREFIX, rather than listing them.
+                  Delete refs which match PREFIX, rather than listing them.  If you are trying to reclaim 
space,
+                 you will then need to <command>ostree prune</command> or <command>ostree admin 
cleanup</command>.
                 </para></listitem>
             </varlistentry>
         </variablelist>