pcr: remove ruby-asciidoctor
    
    asciidoctor is already in Arch Linux community, and it is more
    recent.
    
    On armv7h we have:
        community/asciidoctor 2.0.17-1
            An implementation of AsciiDoc in Ruby
    and on i686 we have:
        community/asciidoctor 2.0.17-1.0 [installed]
            An implementation of AsciiDoc in Ruby
    and on x86_64 we have:
        community/asciidoctor 2.0.17-1
            An implementation of AsciiDoc in Ruby
    
    So we don't need the pakcage from pcr anymore.
    
    Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>