Do a better job with the management of the Kubernetes manifests

Let's have to start all the the Kuberntes manifests embedded as snippets on pages.

But later, need to see where to drop them as files to `curl` (or leverage by #7).

Need to see how to move from bash env to `sed` or even better to `kpt` (#6).

Having a subfolder by chapter with those files? Or a centralized/unique folder with subfolders to be "compliant" with Config Sync (#7)?