Minor improvements to morse-tutorial code.

Author: floitsch

docs/language/package/pkgtutorial.mdx

@@ -315,12 +315,12 @@ It assumes that pin 23 is connected to an LED (and an appropriate resistor).
 LED-PIN ::= 23
 
 main:
-  pin := gpio.Pin.out LED-PIN
+  pin := gpio.Pin --output LED_PIN
 
   10.repeat:
-    morse-tutorial.emit
-        morse-tutorial.encode-string "ababc"
-        --dot-duration= Duration --ms=250
+    morse_tutorial.emit
+        morse_tutorial.encode_string "ababc"
+        --dot_duration= Duration --ms=250
         --on=:  pin.set 1
         --off=: pin.set 0
     sleep (Duration --ms=3000)