Add Dockerfile

[iakat]

If you could enable https://docs.docker.com/docker-hub/builds/, that'd be great!

[SmCTwelve]

Thanks I'll add it!

I'm not sure automated builds will be of any use here. Running the bot requires a Token key which is different per bot account, so I think the image won't run for anyone who downloads it. The repo has no Token just a placeholder. At least with the Dockerfile they can build their own local image using a Token in config.ini or env var.

[iakat]

You can set your own environment variables on Docker, and mount files.
This is how I am running the bot.
By the time I need to set something on config.ini, I'll probably change the code to support env vars instead of reading the config file.
Thanks!