doc: Add auto-generated Wayland Library chapter

For now only Wayland Client API is described on that chapter, which is
extracted via doxygen on ./src/wayland-client.h. We apply a stylesheet
(doxygen-to-publican) on doxygen output so it becomes docbook valid.

Now all we need to do is populate that header while developing in order to
grow a decent documentation. So please use it!

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>