Update any link in `content/*` markdown files that leads to a 404 page

[jamonation]

Here is a set of pages that throw 404 errors that need updating:

jq '.checked [] | select(.status == 404) | {(.url.Path): {"pages":(.parents |keys)}}' links.json
{
  "rekor/how-to-sign-and-upload-metadata-to-rekor/": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "cosign": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "fulcio/how-to-inspect-and-verify-fulcio-certificates/": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "how-to-create-policies-chainguard-enforce-ui": {
    "pages": [
      "content/chainguard/chainguard-enforce/policies/chainguard-enforce-policy-examples.md"
    ]
  }
}
{
  "cosign/how-to-sign-an-sbom-with-cosign/": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/cloud-account-associations": {
    "pages": [
      "content/chainguard/chainguard-enforce/chainguard-enforce-signing/getting-started-chainguard-enforce-signing.md"
    ]
  }
}
{
  "policy-controller": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/understanding-continuous-verification": {
    "pages": [
      "content/chainguard/chainguard-enforce/chainguard-enforce-user-onboarding.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/chainguard-enforce-user-onboarding/": {
    "pages": [
      "content/chainguard/chainguard-enforce/cloudevents/create-github-issues/index.md",
      "content/chainguard/chainguard-enforce/cloudevents/create-jira-issues/index.md",
      "content/chainguard/chainguard-enforce/cloudevents/create-slack-alerts/index.md",
      "content/ui/prerequisites.md"
    ]
  }
}
{
  "chainguard-enforce-policy-examples": {
    "pages": [
      "content/chainguard/chainguard-enforce/policies/chainguard-policies-cli.md"
    ]
  }
}
{
  "policy-controller/how-to-install-policy-controller": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "how-to-keyless-sign-a-container-with-sigstore/": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/chainguard-enforce-rego-policies/": {
    "pages": [
      "content/chainguard/chainguard-enforce/policies/other-policies/k8s-registry-deprecation-policy.md",
      "content/chainguard/chainguard-enforce/policies/other-policies/maximum-image-age-policy.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/log-in-chainguard-enforce/": {
    "pages": [
      "content/chainguard/chainguard-enforce/chainguard-enforce-signing/getting-started-chainguard-enforce-signing.md",
      "content/chainguard/chainguard-enforce/chainguard-enforce-user-onboarding.md"
    ]
  }
}
{
  "fulcio": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}
{
  "/chainguard/chainguard-enforce/chainguard-enforce-kubernetes/understanding-continuous-verification/": {
    "pages": [
      "content/chainguard/chainguard-enforce/chainguard-enforce-user-onboarding.md",
      "content/open-source/sigstore/policy-controller/disallowing-non-default-capabilities-with-policy-controller.md",
      "content/open-source/sigstore/policy-controller/disallowing-privileged-containers-with-policy-controller.md",
      "content/open-source/sigstore/policy-controller/disallowing-run-as-root-user-with-policy-controller.md",
      "content/open-source/sigstore/policy-controller/enforce-sbom-attestation-with-policy-controller.md",
      "content/open-source/sigstore/policy-controller/how-to-install-policy-controller.md",
      "content/open-source/sigstore/policy-controller/maximum-image-age-policy-controller.md",
      "content/open-source/sigstore/policy-controller/using-policy-controller-to-verify-signed-chainguard-images.md",
      "content/open-source/sigstore/policy-controller/warn-deprecated-k8s-registry.md"
    ]
  }
}
{
  "rekor": {
    "pages": [
      "content/open-source/sigstore/_index.md"
    ]
  }
}

[jamonation]

Updated links in #656 - got the list down to these, which come from the images README.md files in https://github.com/chainguard-dev/images/tree/main/images:

jq '.checked [] | select(.status == 404) | {(.url.Path): {"pages":(.parents |keys)}}' links.json
{
  "./examples/": {
    "pages": [
      "content/chainguard/chainguard-images/reference/fluentd/overview.md",
      "content/chainguard/chainguard-images/reference/musl-dynamic/overview.md"
    ]
  }
}
{
  "examples/hello/main.c": {
    "pages": [
      "content/chainguard/chainguard-images/reference/gcc-glibc/overview.md",
      "content/chainguard/chainguard-images/reference/gcc-musl/overview.md"
    ]
  }
}
{
  "examples/hello/main.go": {
    "pages": [
      "content/chainguard/chainguard-images/reference/go/overview.md"
    ]
  }
}
{
  "./example/": {
    "pages": [
      "content/chainguard/chainguard-images/reference/deno/overview.md",
      "content/chainguard/chainguard-images/reference/node/overview.md"
    ]
  }
}
{
  "examples/gnu-hello.yaml": {
    "pages": [
      "content/chainguard/chainguard-images/reference/melange/overview.md"
    ]
  }
}