ui/dbus: clarify the kind of win32 handle that is shared

"-display dbus" hands over a file mapping handle to the peer
process (not a file handle).

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

ui/dbus-display1.xml

@@ -527,14 +527,14 @@
   <interface name="org.qemu.Display1.Listener.Win32.Map">
     <!--
         ScanoutMap:
-        @handle: the shared map handle value.
+        @handle: the shared file mapping handle value (not a file handle)
         @offset: mapping offset.
         @width: display width, in pixels.
         @height: display height, in pixels.
         @stride: stride, in bytes.
         @pixman_format: image format (ex: ``PIXMAN_X8R8G8B8``).
 
-        Resize and update the display content with a shared map.
+        Resize and update the display content with a shared file mapping object.
     -->
     <method name="ScanoutMap">
       <arg type="t" name="handle" direction="in"/>