add what next

Author: MarcScott

buzzer.md

@@ -32,6 +32,7 @@ Set up the circuit as shown below:
         buzzer.on()
 	    sleep(1)
         buzzer.off()
+		sleep(1)
 
     ```
 
@@ -41,3 +42,6 @@ Set up the circuit as shown below:
     while True:
         buzzer.beep()
     ```
+
+## What Next?
+- Have a go at building a [traffic light](trafficlights.md) system using gpiozero.

ldr.md

@@ -64,3 +64,6 @@ Use the following code to set up the light sensor:
 ```
 
 Run this code, then cover the LDR with your hand and watch the value change. Try shining a strong light onto the LDR.
+
+## What Next?
+- You could have a go at using your new knowledge of LDRs to build a [laser-tripwire](https://www.raspberrypi.org/learning/laser-tripwire/).

pir.md

@@ -29,3 +29,6 @@ while True:
     if pir.motion_detected:
         print("You moved")
 ```
+
+## What Next?
+- Now you know how to use a PIR, why not have a go at building a [Parent Detector](https://www.raspberrypi.org/learning/parent-detector)