(1) At Bob Chassell's request, remove leading comments that used to

(1) At Bob Chassell's request, remove leading comments that used to
survive M4 filtering but still tell people the original source was
M4'd;

(2) Also for B.C., include one more emphasis font in @colophon at end;

(3) Thanks to J Gilmore, strengthen wording about unsupported
combinations of host-manufacturer-OS in config Appendix.