xdg-shell: clarify clients set their initial state before initial commit

It wasn't clear that it's important clients set up their initial
xdg_surface state before they send the initial commit. This is
required for the compositor to be able to send a proper configure
event depending on size constraints and any policies it might want
to apply (e.g. specific app ID always shows up in a designated
workspace).

Signed-off-by: Simon Ser <contact@emersion.fr>

stable/xdg-shell/xdg-shell.xml

@@ -434,7 +434,8 @@
       manipulate a buffer prior to the first xdg_surface.configure call must
       also be treated as errors.
 
-      After creating a role-specific object and setting it up, the client must
+      After creating a role-specific object and setting it up (e.g. by sending
+      the title, app ID, size constraints, parent, etc), the client must
       perform an initial commit without any buffer attached. The compositor
       will reply with initial wl_surface state such as
       wl_surface.preferred_buffer_scale followed by an xdg_surface.configure