Update 05-led-roulette/the-challenge.md to the new crate versions.

Author: nikgul

microbit/src/05-led-roulette/the-challenge.md

@@ -25,19 +25,25 @@ you can use the display API provided by the BSP. It works like this:
 use cortex_m_rt::entry;
 use rtt_target::rtt_init_print;
 use panic_rtt_target as _;
+use embedded-hal::delay::DelayNS;
 use microbit::{
     board::Board,
     display::blocking::Display,
-    hal::{prelude::*, Timer},
+    hal::Timer,
 };
 
 #[entry]
 fn main() -> ! {
     rtt_init_print!();
 
     let board = Board::take().unwrap();
+
     let mut timer = Timer::new(board.TIMER0);
     let mut display = Display::new(board.display_pins);
+
+    // Setup the display delay so the math works as expected later.
+    display.set_delay_ms(1);
+
     let light_it_all = [
         [1, 1, 1, 1, 1],
         [1, 1, 1, 1, 1],
@@ -48,9 +54,11 @@ fn main() -> ! {
 
     loop {
         // Show light_it_all for 1000ms
-        display.show(&mut timer, light_it_all, 1000);
+        display.show(&mut timer, light_it_all, 1_000);
+
         // clear the display again
         display.clear();
+
         timer.delay_ms(1000_u32);
     }
 }