Bring tutorials up to date

[meyskens]

Our tutorials have been there for a while, we should go through them again to check:

• is it still the same in the latest Kubernetes/Helm
• Is it still the best practice?
• Are parts out of date due to new APIs/flags?

Tiny bit out of scope but still a nice to have:

• Does it explain cert-manager well? e.g. a lot of users have no idea about the existence off our Certificate CR can we add a tutorial for that?
• Make tutorials less issuer dependant, ingress doesn't need to be ACME for example

[wallrj]

There has been a few improvements to the tutorials:

• Added a Getting Started Guide, which contains a list of known good tutorials
• For those tutorials that we wrote recently, we have added a "Last Verified" header, to give users an indication of how up to date the content is.
  • https://cert-manager.io/docs/tutorials/getting-started-with-cert-manager-on-google-kubernetes-engine-using-lets-encrypt-for-ingress-ssl/
  • https://cert-manager.io/docs/tutorials/getting-started-aks-letsencrypt/
• There have been various updates to the tutorials content https://github.com/cert-manager/website/commits/master/content/docs/tutorials

But the original issue still remains, we should regularly check our tutorials and bring them up to date.