Split out wayland-doc subpackage for documentation
    
    Instead of using a confusingly named 'wayland' subpackage just for
    shipping development documentation, put it in 'wayland-doc' and drop the
    'wayland' subpackage.
    
    As a side effect, this also fixes the build on F24 with rpm 4.12.90
    which would otherwise fail with:
    
    RPM build errors:
        Macro expanded in comment on line 123: #doc %{_datadir}/doc/wayland/*
        Installed (but unpackaged) file(s) found:
       /usr/share/doc/wayland/Wayland/en-US/html/Wayland.proc
       /usr/share/doc/wayland/Wayland/en-US/html/apa.html
       [snip, hundreds of documentation files cut out]