docs: Improve the wl_registry protocol docs
docs: Improve the wl_registry protocol docs

Reword a few things, and add some details.

abooij/wayland,bitfactor/wayland,abooij/wayland,sir-murray/wayland,eyolfson/wayland,bitfactor/wayland,tulcod/wayland,eyolfson/wayland,mchalupa/wayland,sir-murray/wayland,mchalupa/wayland,tulcod/wayland,bitfactor/wayland,abooij/wayland,sir-murray/wayland,eyolfson/wayland,mchalupa/wayland,tulcod/wayland