docs: add aws_load_balancer_controller to the AWS example config

[dcmcand]

Surfaced during review of #259 (pkg/provider/aws/config.go:31).

The aws_load_balancer_controller.{enabled, chart_version} block added in #259 is not currently shown in examples/aws-config.yaml. Until the AWS provider docs are filled out, users have no easy way to discover this is configurable.

Definition of done

• examples/aws-config.yaml includes a commented aws_load_balancer_controller block showing both fields with their defaults
• If an AWS provider doc page exists, it mentions the block too

Review thread: #259 (comment)