* doc/groff.texinfo: Don't use the string `Appendix' for appendix
headers (both in the text and the table of contents).
* man/groff_tmac.man, src/roff/troff/troff.man: Fix order of tmac
directories.
Use registers LL and LT (similar to -ms) for controlling the
length of title and line, respectively, in the -man and -mdoc
macro packages.
* tmac/doc-ditroff (doc-setup-page-layout), tmac/doc-nroff
(doc-setup-page-layout): Use \n[LL] and \n[LT].
* tmac/an-old.tmac: Set \n[LL] and \n[LT] if not defined.
(TH): Use \n[LL].
(an-header, an-p-footer): Use \n[LT].
* NEWS, tmac/groff_man.man, tmac/groff_mdoc.man,
doc/groff.texinfo: Document it.