man/l_roff-char.7.in: fix Bernd Warken (Dave Kemper, Werner Lemberg)..

man/l_roff-char.7.in: fix Bernd Warken (Dave Kemper, Werner Lemberg)..

Dave Kemper (saint dot snit at gmail dot com) reported on groff@

 |> groff_char does seem to address this issue regarding other glyphs.  It
 |> says, "Entries marked with `***' denote glyphs for mathematical

 |I was finally going to do this but hit a snag: it turns out commit
 |07a6233adeb476611f7a286295935cbbf6b9cbbd ("complete notes in tables,"
 |done by Bernd Warken) removed the *** marker from all rows that
 |previously contained it, while leaving the explanatory text of what
 |the marker signifies.

That one i blindly take!
I first posted a patch only with that, and Werner Lemberg
responded:

  > I wonder what those "+" markers are for, they have been added in
  > [48615a4].

  Uh, oh, a lot of them are lost :-( As documented in the man page, they
  indicate that the (two-letter) glyph name is documented in the
  original troff manual.

  I fear that Bernd won't be able to fix this due to personal issues, so
  maybe someone can check the groff_char man page from version 1.22.2,
  re-adding the plus signs.

So indeed it is documented, but not using the plus symbol only the
word plus, which i haven't searched for.
Bring this back to life as such.