During a review of the Knative docs repository, I identified several genuine broken or outdated links that require attention:

1. Outdated Kubernetes API Documentation Links (CRITICAL)

    Location: Multiple API reference documents
    Broken URL Pattern: https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#*
    Issue: The docs are linking to the now-broken v1.18 Kubernetes API documentation.
    
    Old (broken) example:
    [https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#objectmeta-v1-meta](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#objectmeta-v1-meta)
    New (working) example:
    [https://kubernetes.io/docs/reference/kubernetes-api/common-definitions/object-meta/](https://kubernetes.io/docs/reference/kubernetes-api/common-definitions/object-meta/)
   

2. Outdated Slack URLs
   Still provides links to knative.slack.com, which requires an existing account.
   Correct process: Slack has migrated—should direct users to the invitation/signup page:
   Signup: https://slack.cncf.io/
   Current channel example: https://cloud-native.slack.com/archives/C04LY5G9ED7 for #knative-documentation

3. Docker Registry URL
   Historical issue: https://index.docker.io/v1/ caused link checker failures in the past.
   Location: docs/serving/deploying/private-registry.md