Correct documentation for pxe_default_server, pxe_default_gatway and pxe_blksize. Only pxe_default_server is actually used (alias for net_default_server). So, capture this and remove the other two. Fixes: https://savannah.gnu.org/bugs/?54480 Signed-off-by: Andrew Hamilton <adhamilt@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>