Updated Hardware API (markdown)

Hardware-API.md

@@ -79,7 +79,7 @@ one can easily see what's supported on the board.
 An interrupt request (IRQ) is an asynchronous and pre-emptive action triggered by a peripheral.  Peripherals that support interrupts provide the `irq` method which returns an irq object.  This can be used to execute a function when an IRQ is triggered, or wake up the device, or both.
 
 ```python
-peripheral.irq(*, trigger=None, priority=1, handler=None, wake=None)
+peripheral.irq(*, trigger, priority=1, handler=None, wake=None)
 ```
 
 - All arguments are keyworkd only, to be able to adapt to the different nature of each peripheral.