tmac/tmac.an: define .MR in a groff compatible way

groff 1.23.0 added .MR to its -man macro package.  The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020."  From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.

Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.

Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized.  groff's .MR does not.  This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.

1 files changed, 4 insertions, 4 deletions

diff --git a/man/man1/soelim.1 b/man/man1/soelim.1
index c7324035..545883b7 100755
--- a/man/man1/soelim.1
+++ b/man/man1/soelim.1
@@ -11,19 +11,19 @@ soelim \- preprocess so inclusion commands in troff input
 .I Soelim
 reads the specified files or the standard input and performs
 the textual inclusion implied by
-.MR troff (1)
+.MR troff 1
 directives of the form
 .TP
 .B "\&.so some_file
 .PP
 when they appear at the beginning of input lines.  This is useful when
 using programs such as
-.MR tbl (1)
+.MR tbl 1
 that do not normally do this, allowing
 placement of individual tables or other text objects in separate files
 to be run as a part of a large document.
 .SH SOURCE
 .B \*9/bin/soelim
 .SH "SEE ALSO"
-.MR deroff (1) ,
-.MR troff (1)
+.MR deroff 1 ,
+.MR troff 1