Improve docs

[Azelphur]

This will be a draft until I've gone through my setup process, but since I'm using the documentation, while I'm here, I'll help fix any bits I spot :)

List of things I spotted:

• On https://tech7fox.github.io/sip-hass-docs/docs/developers/add-on#running-locally-with-docker it mentions copying asterisk/config.json.example but that doesn't exist any more, I've edited it to what I believe is correct