Update to correct Docbook stylesheets
    
    Docbook5 stylesheets with namespaces are required. BIND uses Docbook5
    format. While it tries to keep compatibility with older stylesheets,
    it fails silently and format of manual pages is broken.
    
    Details in upstream issue:
    https://gitlab.isc.org/isc-projects/bind9/-/issues/2310
    
    Docbook5 generates manual pages with [FIXME: manual] instead of BIND9.
    Fix metadata to be recognized and provide this value.