docs(orc8r): improve Minikube deployment guide

[AmraniCh]

Context

This PR follows #16032 and updates the existing Orc8r Minikube deployment guide.

The current documentation uses Kubernetes v1.20, which is no longer supported by modern Minikube releases. The guide has been updated to use Kubernetes v1.28 and to reflect the steps required to deploy Orc8r successfully on a current Minikube environment.

Summary

This PR improves the Orc8r Minikube deployment guide by:

• Updating the Kubernetes version from v1.20 to v1.28.
• Documenting the compatible kubectl version range.
• Clarifying the required prerequisites.
• Pinning Fluentd Ruby dependency versions to ensure compatible container builds (we can remove this after the PR #15699 get merged).
• Fixing certificate permission issues caused by Docker creating the certificate files as root before applying the certificates.
• Adding an optional LTE chart installation example to demonstrate how additional Orc8r functionality can be deployed.

Test Plan

Followed the updated guide and validated the deployment on Kubernetes v1.28.0 using Minikube.

Verified that the Orc8r Helm charts can be installed and the required pods reach the Running state.

Additional Information

The Kubernetes v1.28 deployment relies on the Helm chart API updates introduced in #16032.

Security Considerations

No security impact.