Docs: Instances, or the `‐‐instance` flag for CLI commands

Maybe you've seen the --instance flag in a few of the commands, in many cases it's a required flag, or maybe you've seen it mentioned in other documentation. The easiest way to think of instances is:

1. If you're a user of this project
   • You don't have to worry about anything other instance 1
   • You can use optionally use instance 2 or 3 if you wish to have copy multiple copies, one for experimental edits, and one for your main work in a safe predictable state.
2. If you're working on this project
   • Use 1 for any analysis
   • Use 2 or 3 for any feature development
     • 2 ingests a subset of data for speed
     • 3 exists incase you want to multitask something crazy without blocking feature development using instance 2

In theory these should just be called environments, and maybe I should rename them like

• instance 1 should be production
• instance 2 should be staging
• instance 3 should be development

But when I set these up it never crossed my mind this was what I was doing. But in practice, I typically alternate between 2 & 3 during development at my own convenience... 1 is generally tho production of stable data.