fix mdbook redirection table (#1635)

Link `overloading` in Speaker note in URL:
https://google.github.io/comprehensive-rust/hello-world/hello-world.html
is broken.

- broken:
https://google.github.io/comprehensive-rust/hello-world/basic-syntax/functions-interlude.html
(404)
- correct:
https://google.github.io/comprehensive-rust/control-flow-basics/functions.html

The reason why it is broken is below.

Original markdown is here
43474d27d1/src/hello-world/hello-world.md (L36-L37)

```
[overloading](basic-syntax/functions-interlude.md)
```

Page path is `/hello-world/hello-world.html`, so overloading link become
`/hello-world/basic-syntax/functions-interlude.html`, which is 404.

I feel it is better to use redirect to exact path, so I edit `book.toml`
and make link redirect to `/basic-syntax/functions-interlude.html`,
which re-redirect to path `/control-flow-basics/functions.html`


43474d27d1/book.toml (L114)

book.toml

@@ -73,6 +73,7 @@ use-boolean-and = true
 "exercises/concurrency/elevator.html" = "chat-app.html"
 "generics/closures.html" = "../traits/closures.html"
 "generics/trait-objects.html" = "../traits/trait-objects.html"
+"hello-world/basic-syntax/functions-interlude.html" = "../../control-flow-basics/functions.html"
 "outros-recursos.html" = "other-resources.html"
 "running-the-course/day-4.html" = "course-structure.html"
 "sintaxe-básica/funções-interlude.html" = "../basic-syntax/functions-interlude.html"

src/hello-world/hello-world.md

@@ -34,7 +34,7 @@ Key points:
 - Rust is modern with full support for things like Unicode.
 
 - Rust uses macros for situations where you want to have a variable number of
-  arguments (no function [overloading](basic-syntax/functions-interlude.md)).
+  arguments (no function [overloading](../control-flow-basics/functions.md)).
 
 - Macros being 'hygienic' means they don't accidentally capture identifiers from
   the scope they are used in. Rust macros are actually only