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, 6 insertions, 6 deletions

diff --git a/man/man1/kill.1 b/man/man1/kill.1
index f82b4877..119a69db 100644
--- a/man/man1/kill.1
+++ b/man/man1/kill.1
@@ -19,18 +19,18 @@ prints commands that will cause all processes with
 .I name
 and owned by the current user to be terminated.
 Each command is commented with an output line from
-.MR ps (1)
+.MR ps 1
 describing the process that would be killed.
 Use the
 .B send
 command of
-.MR 9term (1) ,
+.MR 9term 1 ,
 or pipe the output of
 .I kill
 into
-.MR rc (1)
+.MR rc 1
 or
-.MR sh (1)
+.MR sh 1
 to execute the commands.
 .PP
 .I Kill
@@ -60,8 +60,8 @@ signal.
 .SH SOURCE
 .B \*9/bin
 .SH "SEE ALSO"
-.MR ps (1) ,
-.MR notify (3)
+.MR ps 1 ,
+.MR notify 3
 .SH BUGS
 .I Stop
 and