docs/wipy/tutorial: Add note about screen key bindings on OS X.

docs/wipy/tutorial/repl.rst

@@ -52,7 +52,12 @@ or::
 
     $ screen /dev/tty.usbmodem* 115200
     
-When you are finished and want to exit screen, type CTRL-A CTRL-\\.
+When you are finished and want to exit ``screen``, type CTRL-A CTRL-\\. If your keyboard does not have a \\-key (i.e. you need an obscure combination for \\ like ALT-SHIFT-7) you can remap the ``quit`` command:
+
+- create ``~/.screenrc``
+- add ``bind q quit``
+
+This will allow you to quit ``screen`` by hitting CTRL-A Q.
 
 Linux
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