manpage: minor fixes

Also update the Lua example. The "pause" event was declared deprecated,
so the example should use the newer API.
vo_wayland: Add "multimedia" keyboard key bindings.

libxkbcommon keysyms are the same as X11 keysyms (sans prefix),
so I simply copied the missing subsection from x11_common.c.

Signed-off-by: Sergey Kvachonok <ravenexp@gmail.com>
Signed-off-by: wm4 <wm4@nowhere>