Update lib.rs, added info that needed panic messages can be found in …

…the tests. (#157)

exercises/03_ticket_v1/02_validation/src/lib.rs

@@ -12,6 +12,7 @@ impl Ticket {
     //   - the `title` should be at most 50 bytes long.
     //   - the `description` should be at most 500 bytes long.
     //  The method should panic if any of the requirements are not met.
+    //  You can find the needed panic messages in the tests.
     //
     // You'll have to use what you learned in the previous exercises,
     // as well as some `String` methods. Use the documentation of Rust's standard library