expand on displaying map with xterm

README.md

@@ -46,7 +46,8 @@ room number, which you can find with `#map info` when you're in the room with th
         mapout /tmp/map.out
         ```
 
-     2. Display the map, open up a new terminal emulator. You might use xterm:
+     2. Display the map, open up a new terminal emulator and follow the file with
+        `tail -f`. You might use xterm:
         ```
         xterm -geometry 60x20 -rv +sb
         tail -f /tmp/map.out 2>/dev/null