Add doc, simplify docker, update chart
 - add doc on how to setup the TMPDIR environment variable
 - simplify docker compose
 - update chart to use the four new environment variables
 - upgrade some minor dependencies

(sorry, it's a mix of too many things, should have been various PRs)
Add doc, simplify docker, update chart:  - add doc on how to setup the TMPDIR environment variable
 - simplify docker compose
 - update chart to use the four new environment variables
 - upgrade some minor dependencies

(sorry, it's a mix of too many things, should have been various PRs)