river-status: note that wl_outputs must be bound

 protocol/river-status-unstable-v1.xml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/protocol/river-status-unstable-v1.xml b/protocol/river-status-unstable-v1.xml
index a4d6f4e..93040cd 100644
--- a/protocol/river-status-unstable-v1.xml
+++ b/protocol/river-status-unstable-v1.xml
@@ -80,7 +80,8 @@
   <interface name="zriver_seat_status_v1" version="1">
     <description summary="track seat focus">
       This interface allows clients to receive information about the current
-      focus of a seat.
+      focus of a seat. Note that (un)focused_output events will only be sent
+      if the client has bound the relevant wl_output globals.
     </description>
 
     <request name="destroy" type="destructor">