doc/tmac.n: Fix erroneous lines.

I'm mindful of the license here, but suspect that these lines crept in
after Matt Bishop's time.  Text lines in a macro package can be
insidious because they cause formatting operations to start even in the
absence of an input document.  The forthcoming groff 1.24 has a new
diagnostic to help catch these situations.

The groff Texinfo manual says:

     A '\"' comment on a line by itself is treated as a blank line,
     because after eliminating the comment, that is all that remains.

          Test
          \" comment
          Test
              => Test
              =>
              => Test

     To compensate, it is common to combine the empty request with the
     comment escape sequence as '.\"', causing the input line to be
     ignored.

Fixes:

$ (cd doc && groff -t -M . -mn -mnh Guidebook.mn > /dev/null)
troffrc:./tmac.n:1: text line in startup file
troffrc:./tmac.n:764: text line in startup file

doc/tmac.n

@@ -1,4 +1,4 @@
-\" @(#)$Id: tmac.n,v 1.4 2002/01/19 13:41:15 michael.allison Exp $
+.\" @(#)$Id: tmac.n,v 1.4 2002/01/19 13:41:15 michael.allison Exp $
 .\" The News macro package
 .\"
 .\" This  is  the macro package that is used to format news documents.  It
@@ -761,4 +761,3 @@
 .\" couple of miscellaneous requests
 .bd S 3 3				\" embolden special font chars if B
 .hy 2					\" don't hyphenate last lines
-