fix: documentation links

Signed-off-by: Mateus Oliveira <msouzaol@redhat.com>

docs/README.md

@@ -2,7 +2,7 @@
 
 The kubebuilder book is served using [mdBook](https://github.com/rust-lang-nursery/mdBook). If you want to test changes to the book locally, follow these directions:
 
-1. Follow the instructions at [https://github.com/rust-lang-nursery/mdBook#installation](https://github.com/rust-lang-nursery/mdBook#installation) to
+1. Follow the instructions at [https://rust-lang.github.io/mdBook/guide/installation.html](https://rust-lang.github.io/mdBook/guide/installation.html) to
    install mdBook.
 2. Make sure [controller-gen](https://pkg.go.dev/sigs.k8s.io/controller-tools/cmd/controller-gen) is installed in `$GOPATH`.
 3. cd into the `docs/book` directory

docs/book/theme/index.hbs

@@ -133,7 +133,7 @@
                             </button>
                             <div class="version-dropdown-content">
                                 <a href="https://book.kubebuilder.io/"target="_blank" rel="noopener noreferrer">latest (v4-book)</a>
-                                <a href="https://book-v3.kubebuilder.io/"target="_blank" rel="noopener noreferrer">v3-book</a>
+                                <a href="https://book-v3.book.kubebuilder.io/"target="_blank" rel="noopener noreferrer">v3-book</a>
                                 <a href="https://book-v2.book.kubebuilder.io/"target="_blank" rel="noopener noreferrer">v2-book</a>
                                 <a href="https://book-v1.book.kubebuilder.io/"target="_blank" rel="noopener noreferrer">v1-book</a>
                             </div>