wp_viewport: Odd description of wl_surface.attach x/y behavior.

wl_surface.attach's x/y arguments offset the surface position with the sole purpose of allowing a surface to grow towards the left and towards the top when increasing its size.

wp_viewport says the following about wl_surface.attach's x and y arguments:

The x, y arguments of wl_surface.attach are applied as normal to
the surface. They indicate how many pixels to remove from the
surface size from the left and the top.

This could be interpreted as a sort of cropping operation, rather than the intended move operation. It would be simpler to just avoid describing how wl_surface.attach x/y works, at most specifying that the definition of surface-local coordinates remain unchanged.