doc: fix a typo in the rtcinterrupt example (#3981)

docs: fix a typo in the rtcinterrupt example, also provide a link to the interrupt online doc

Author: graugans

src/examples/rtcinterrupt/rtcinterrupt.go

@@ -24,7 +24,9 @@ func main() {
 
 	// Schedule and enable recurring interrupt.
 	// The callback function is executed in the context of an interrupt handler,
-	// so regular restructions for this sort of code apply: no blocking, no memory allocation, etc.
+	// so regular restrictions for this sort of code apply: no blocking, no memory allocation, etc.
+	// Please check the online documentation for the details about interrupts:
+	// https://tinygo.org/docs/concepts/compiler-internals/interrupts/
 	delay := time.Minute + 12*time.Second
 	machine.RTC.SetInterrupt(uint32(delay.Seconds()), true, func() { println("Peekaboo!") })