docs/pyboard: Fix typo in pyb.Switch tutorial.
@@ -93,7 +93,7 @@ on the pin for any changes, and the following will occur:
running Python script.
3. The microcontroller starts executing the special interrupt handler
associated with the switch's external trigger. This interrupt handler
- get the function that you registered with ``sw.callback()`` and executes
+ gets the function that you registered with ``sw.callback()`` and executes
it.
4. Your callback function is executed until it finishes, returning control
to the switch interrupt handler.
