fixed typo

examples/timing_exam.rs

@@ -116,7 +116,7 @@ const APP: () = {
 // Now its time to see if your scheduling analysis is accurate
 // in comparison to a real running system.
 //
-// First explain in your own words how the `Instance` is
+// First explain in your own words how the `Instant` is
 // used to generate a periodic task instance arrivals.
 //
 // `cx.schedule.t1(cx.scheduled + 100_000.cycles()).unwrap();`
@@ -125,7 +125,7 @@ const APP: () = {
 //
 // Explain in your own words the difference between:
 //
-// `cx.schedule.t1(Instance::now() + 100_000.cycles()).unwrap();`
+// `cx.schedule.t1(Instant::now() + 100_000.cycles()).unwrap();`
 // and
 // `cx.schedule.t1(cx.scheduled + 100_000.cycles()).unwrap();`
 //
@@ -138,10 +138,10 @@ const APP: () = {
 //
 // Hint, look at https://rtic.rs/0.5/book/en/by-example/timer-queue.html
 //
-// Once you understand how `Instance` is used, document your crate:
+// Once you understand how `Instant` is used, document your crate:
 // > cargo doc --open
 //
-// Once you have the documentation open, search for `Instance`
+// Once you have the documentation open, search for `Instant`
 // Hint, you can search docs by pressing S.
 //
 // Now figure out how to calculate the actual response time.