Update GitBook URL to point to netlify served pages instead of (#1013)

* Update GitBook URL to point to netlify served pages instead of
gh-pages.

* Make URLs links.

* Update README.md

Co-Authored-By: Jason DeTiberus <[email protected]>

* Update docs/book/README.md

Co-Authored-By: Jason DeTiberus <[email protected]>

Author: 2 people

README.md

@@ -78,7 +78,7 @@ Following are the implementations managed by third-parties adopting the standard
 
 ### Resources
 
-* GitBook: [kubernetes-sigs.github.io/cluster-api](https://kubernetes-sigs.github.io/cluster-api)
+* GitBook: [cluster-api.sigs.k8s.io](https://cluster-api.sigs.k8s.io)
 
 ### Prerequisites
 * `kubectl` is required, see [here](http://kubernetes.io/docs/user-guide/prereqs/).

docs/book/README.md

@@ -57,7 +57,7 @@ reliability.
 
 ## Resources
 
-- GitBook: [kubernetes-sigs.github.io/cluster-api](https://kubernetes-sigs.github.io/cluster-api)
+- GitBook: [cluster-api.sigs.k8s.io](https://cluster-api.sigs.k8s.io)
 - GitHub Repo: [kubernetes-sigs/cluster-api](https://github.com/kubernetes-sigs/cluster-api)
 - Slack channel: [#cluster-api](http://slack.k8s.io/#cluster-api)
 - Google Group: [[email protected]](https://groups.google.com/forum/#!forum/kubernetes-sig-cluster-lifecycle)