[muji/master] reword initial How it Works paragraph

[Dafydd Harries]

---
 xep/mingle.xml |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/xep/mingle.xml b/xep/mingle.xml
index d5ffdc5..4eb7dcc 100644
--- a/xep/mingle.xml
+++ b/xep/mingle.xml
@@ -45,10 +45,11 @@ Mingle conferences are held in <cite>XEP-0045</cite> rooms.
 
 <section1 topic="How it works" anchor="howitworks">
 Mingle works by having all participants in a conference announce the
-definitions of the content that they provide in their MUC presence. This is
-used to build a global payload type (PT) mapping for the various contents,
-which is then used to initiate normal Jingle sessions. The global mapping
-allows each participant to encode and payload each content only once.
+definitions of the content that they provide in their MUC presence. This
+serves two purposes. Firstly, so that each participant knows which contents
+every other participant provides. Secondly, so that there is a global payload
+type (PT) mapping for the various contents, so that clients only need to
+encode and payload each content that they provide once.
 
 Participants can participate in a read-only mode by not advertising any
 contents. Participants are not obliged to initiate Jingle sessions with all
-- 
1.5.6.5