ivi-shell: describe members of type wl_list

I wrote comments on which list they are used with

Signed-off-by: Emre Ucan <eucan@de.adit-jv.com>
[Pekka: fix surface_list to layer_list, add ivi_layout_transition_set::transition_list]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/ivi-shell/ivi-layout-transition.c b/ivi-shell/ivi-layout-transition.c
index bf0640e..b887ff6 100644
--- a/ivi-shell/ivi-layout-transition.c
+++ b/ivi-shell/ivi-layout-transition.c
@@ -60,6 +60,10 @@
 
 struct transition_node {
 	struct ivi_layout_transition *transition;
+
+	/* ivi_layout::pending_transition_list
+	 * ivi_layout_transition_set::transition_list
+	 */
 	struct wl_list link;
 };