Fix CRD installation path in aws-load-balancer-controller README

[yukin01]

Issue

N/A

Description of changes

Fixed incorrect kustomize path for CRD installation in the upgrade guide.
The double slashes should appear after the repository name, not within the path components.

Before:

kubectl apply -k "github.com/aws/eks-charts/stable/aws-load-balancer-controller//crds?ref=master"

After:

kubectl apply -k "github.com/aws/eks-charts//stable/aws-load-balancer-controller/crds?ref=master"

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

Verified the correct kustomize path structure by checking the repository layout.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.