quickstart docker examples does not work

**Which example does this problem concern?**
quick-start docker

**Please describe the problem?**

1. example documentation is missing step to execute `generate-keys.sh`
2. docker-compose.yml pins version to 0.4.1, should be empty to pull latest
3. containerssh exits with code 1 on `unsupported host key algorithm ecdsa-sha2-nistp256 on host key 1` for both 0.4.1 and 0.5.2 image versions