Link directly to `String` type.

diff --git a/book/src/03_ticket_v1/02_validation.md b/book/src/03_ticket_v1/02_validation.md
index 866dd2c..7af7a1f 100644 (file)
--- a/book/src/03_ticket_v1/02_validation.md
+++ b/book/src/03_ticket_v1/02_validation.md
@@ -21,5 +21,5 @@ We can do better than that!
 
 ## Further reading
 
-- Check out [`String`'s documentation](https://doc.rust-lang.org/std/string/index.html) 
+- Check out [`String`'s documentation](https://doc.rust-lang.org/std/string/struct.String.html) 
   for a thorough overview of the methods it provides. You'll need it for the exercise!
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