with some small and some large changes.

A summary is:
- Bump up from stable-8719 to stable-8960-1
- Add /config as emptyDir, to support readOnlyRootFilesystem
- Make defaults config and cont-init scripts customize at deploy time
- Add nodePorts for Prosody and Web for restricted Kubernetes
  deployments
- Add example configurations, and Makefile, to test changes quickly

There are cases where we may prefer to create common secrets
outside the chart and override values filled from configmaps
or secrets created from this chart.

Common usecases would be Hashicorp Vault/ 1Password operator
integrations.

This commits makes such overrides possible.