allow uuid being created and managed by kubernetes

[colearendt]

What this PR does / why we need it:

We utilize Helm's lookup command to store a generated uuid in an "internal" secret in Kubernetes. This allows generating the uuid, making it persistent, and notifying the user (in NOTES.txt) that this auto-generation happened. We also tell the user how to disable the message by making that value persistent in values.

Which issue this PR fixes

• fixes A value for couchdbConfig.couchdb.uuid must be set #39
• supersedes / related to No HTTP call to a third-party to generate a random UUID #50

Special notes for your reviewer:

Happy to discuss this approach, messaging, etc. We have found similar patterns to strike a decent balance when secrets / inputs must exist outside of the application.

Open question: should we allow dangerRegenerateAutomatedValues?

(will walk through checklist once validated as a decent approach)

TODO: update docs accordingly / remove the uuid generation

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.

• Chart Version bumped
• e2e tests pass
• Variables are documented in the README.md
• Chart tgz added to /docs and index updated