Minor enhancements

[maroskukan]

Hello, thanks for this tool,

I would like to propose the following changes/enhancements:

docs/examples/docker/README.md

• added working directory to "medusa" function - this makes the volume mount more useful as the paths inside and outside of containers are same. Its now easy to reference a file on host and use it inside the container e.g. import files
• added example for medusa import when invoked through docker container

scripts/start-vault.sh

• update the image path to hashicorp/vault:latest for "Vault status" invocation
• add .env file generation, which is useful when using docker container which maps these values between host and container. user is still required to source this env file . ./.env or use some tool that does it automatically
• backup existing configuration file for medusa if present - saves from accidental overwrite of previous configuration