Fix URL for the Gitbook
The URL is .io, not .com
@@ -39,7 +39,7 @@ Including:
## Resources
-GitBook: [book.kubebuilder.com](http://book.kubebuilder.com)
+GitBook: [book.kubebuilder.io](http://book.kubebuilder.io)
GitHub Repo: [kubernetes-sigs/kubebuilder](https://github.com/kubernetes-sigs/kubebuilder)
Slack channel: [#kubeuilder](http://slack.k8s.io/#kubebuilder)
Google Group: [kubebuilder@googlegroups.com](https://groups.google.com/forum/#!forum/kubebuilder)
