Figure out ownership of learn materials or delete

Following the tutorial here:
https://www.envoyproxy.io/learn/ssl

I've got this error:

```
front-envoy_1 | [2020-01-12 07:54:22.719][6][critical][main] [source/server/server.cc:94] error initializing configuration '/etc/front-envoy.yaml': Protobuf message (type envoy.config.bootstrap.v3alpha.Bootstrap reason INVALID_ARGUMENT:(static_resources.listeners[0].filter_chains[1]) tls_context: Cannot find field.) has unknown fields
front-envoy_1 | [2020-01-12 07:54:22.719][6][info][main] [source/server/server.cc:595] exiting
front-envoy_1 | Protobuf message (type envoy.config.bootstrap.v3alpha.Bootstrap reason INVALID_ARGUMENT:(static_resources.listeners[0].filter_chains[1]) tls_context: Cannot find field.) has unknown fields
```

With this settings on the envoy front-end:

```yaml
- tls_context:
common_tls_context:
tls_certificates:
- certificate_chain:
filename: "/etc/listener.crt"
private_key:
filename: "/etc/listener.key"
```