index: rewrite the introduction
This was inspsired by a recent IRC discussion where I once again explained what Wayland is, and triggered by the IRC comment
< MrCooper> heh, https://wayland.freedesktop.org/ says "GNOME and KDE are
expected to be ported to it."
< MrCooper> should be any day now
I tried to make the explanation more understandable, including what Wayland is and what it is not.