use macro for /usr/local/plan9

man/man1/acme.1

@@ -463,15 +463,15 @@ will produce the output
 in a (possibly newly-created) window labeled
 .BR /adm/+Errors ;
 in a window containing
-.B /usr/local/plan9/src/cmd/sam/sam.c
+.B \*9/src/cmd/sam/sam.c
 executing
 .B mk
 will run
 .IR mk (1)
 in
-.BR /usr/local/plan9/src/cmd/sam ,
+.BR \*9/src/cmd/sam ,
 producing output in a window labeled
-.BR /usr/local/plan9/src/cmd/sam/+Errors .
+.BR \*9/src/cmd/sam/+Errors .
 The environment of such commands contains the variable
 .B $%
 with value set to the filename of the window in which the command is run.
@@ -675,11 +675,11 @@ source for applications
 .B /acme/*/mips
 MIPS-specific binaries for applications
 .SH SOURCE
-.B /usr/local/plan9/src/cmd/acme
+.B \*9/src/cmd/acme
 .br
-.B /usr/local/plan9/src/cmd/9term/win.c
+.B \*9/src/cmd/9term/win.c
 .br
-.B /usr/local/plan9/bin/awd
+.B \*9/bin/awd
 .SH SEE ALSO
 .IR acme (4)
 .br