fixup! feat(examples): add a more interesting benchmark

examples/benchmark/src/main.rs

@@ -8,13 +8,8 @@ use riot_rs::debug::println;
 #[riot_rs::thread]
 fn main() {
     match riot_rs::bench::benchmark(1000, || {
-        let mut i = 0;
-
-        // This seems to be measuring branching cost more than anything
-        for _ in 0..1000 {
-            i += 1;
-            core::hint::black_box(i);
-        }
+        // Insert the function to benchmark here.
+        // Consider using `core::hint::black_box()` where necessary.
     }) {
         Ok(ticks) => {
             println!("took {} per iteration", ticks);