Migrate docs from the other repo

docs/reference/js/lessons/running-time/challenges.md

@@ -0,0 +1,30 @@
+# running time challenges
+
+My script. #docs
+
+**Challenge 0**
+
+Great job! You have successfully completed the [Running Time tutorial](/microbit/lessons/running-time/tutorial) . You have a forever loop that declares a variable in it that holds the running time in milliseconds of the micro:bit and then shows the seconds on the LED screen.
+
+```
+basic.forever(() => {
+    let now = input.runningTime()
+    basic.showNumber(now / 1000, 150)
+})
+```
+
+**Challenge 1**
+
+When button A is pressed, reset the time by subtracting the current time from the variable now.
+
+```
+basic.forever(() => {
+    let now1 = input.runningTime()
+    basic.showNumber(now1 / 1000, 150)
+})
+if (input.buttonIsPressed("A")) {
+    let now2 = 0 // ***
+}
+```
+
+* Run the code to see if it works as expected.