miniterm: fix double use of CTRL-T + s

use z for suspend instead

fixes #497
diff --git a/documentation/tools.rst b/documentation/tools.rst
index 8ed7fce..898c2d7 100644
--- a/documentation/tools.rst
+++ b/documentation/tools.rst
@@ -274,7 +274,7 @@
     ---    x X        disable/enable software flow control
     ---    r R        disable/enable hardware flow control
 
-:kbd:`Ctrl+T s` suspends the connection (port is opened) and reconnects when a
+:kbd:`Ctrl+T z` suspends the connection (port is opened) and reconnects when a
 key is pressed. This can be used to temporarily access the serial port with an
 other application, without exiting miniterm. If reconnecting fails it is
 also possible to exit (:kbd:`Ctrl+]`) or change the port (:kbd:`p`).
diff --git a/serial/tools/miniterm.py b/serial/tools/miniterm.py
index 2ec155e..13d0cdd 100644
--- a/serial/tools/miniterm.py
+++ b/serial/tools/miniterm.py
@@ -589,7 +589,7 @@
         #~ elif c == '\x0c':                       # CTRL+L -> cycle linefeed mode
         elif c in 'pP':                         # P -> change port
             self.change_port()
-        elif c in 'sS':                         # S -> suspend / open port temporarily
+        elif c in 'zZ':                         # S -> suspend / open port temporarily
             self.suspend_port()
         elif c in 'bB':                         # B -> change baudrate
             self.change_baudrate()