How to config redis connection with password and tls/ssl

[kondohiroki]

[Valian]

@hirkkondo It seems https://github.com/auto-ssl/lua-resty-auto-ssl#redis auth option is not yet covered by environment variables. It has to be added to resty-http snippet, entrypoint, Dockerfile and readme, and then it should be possible. I would gladly accept PR, as I've done with the initial Redis support request.