Manifest unknown for Envoy proxy

Ran
```
docker-compose up -d                                    
```
but got error
```
Pulling envoy (envoyproxy/envoy:latest)...
ERROR: manifest for envoyproxy/envoy:latest not found: manifest unknown: manifest unknown
```

Fixed by changing image from `envoyproxy/envoy:latest` to `envoyproxy/envoy:v1.14-latest`