feat: add multi-ingress support documentation

[myk0la-b]

Resolves portainer/k8s#173

Summary

• The Helm chart now supports defining multiple Kubernetes Ingress resources using the existing ingress key.
• ingress can be either a single object (legacy behavior) or an array (for multiple Ingress resources).
• The chart template logic and documentation have been updated accordingly.
  Details
• If ingress is an array, each entry results in a separate Ingress resource (e.g., for HTTP and HTTPS, or multiple hosts).
• If ingress is a map/object, the chart behaves as before, creating a single Ingress resource.
• All documentation and examples in README.md and values.yaml have been updated to reflect this change.
• Chart version bumped to 1.0.67.
  Why?
  This change allows users to manage multiple Ingress resources (e.g., for different ports, hosts, or controllers) in a single Helm release, improving flexibility and maintainability.