create Cilium ingress tls example

[jahrlin]

Cilium has a few example configurations in their repo, including one for Cilium ingress + TLS with self-signed certificates: https://github.com/cilium/cilium-service-mesh-beta/blob/main/kubernetes-ingress/tls.md

We want to create another example with the same format and scope as the above mentioned example, but using cert-manager to issue LE-certs.

Expected outcome is:

• [x] a PR on Cilium's repo to add the example.
• [ ] a new page in this section https://cert-manager.io/docs/tutorials/ that links to the new example.