adding k8s docs and a more generalized doc

I recently went through some pain in getting Tranquil all set up on my k8s cluster. Luckily some of my 'biggest' pain was in the mystery of the email server, which has been resolved in the meantime. Regardless, I added a bunch more detail on a somewhat generic k8s deployment, with some context for secrets, secret generation, etc. I also set up a "general configuration" doc that took some of the details and context from all the install-x docs and compiled it together into a more generalized information source with all the env vars I could find centralized into one place. Sorry if this kind of work is already being done elsewhere, I wanted to get this somewhere so I can point friends to so they do their own PDS.