tmac: rename IM (italic manual) to MR (manual reference)

Suggested by G. Brandon Robinson.

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
-.IM ps (1)
+.MR ps (1)
 describing the process that would be killed.
 Use the
 .B send
 command of
-.IM 9term (1) ,
+.MR 9term (1) ,
 or pipe the output of
 .I kill
 into
-.IM rc (1)
+.MR rc (1)
 or
-.IM 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"
-.IM ps (1) ,
-.IM notify (3)
+.MR ps (1) ,
+.MR notify (3)
 .SH BUGS
 .I Stop
 and