Improve provisioner docs

[pleshakov]

Proposed changes

Problem:
It is not obvious that it is necessary to re-build the NKG image to customize the static mode Deployment, which the provisioner uses.

Solution:
Make the docs clearer.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork