fix broken references to deleted page

Author: shanhix1

articles/governance/policy/index.yml

@@ -69,8 +69,6 @@ landingContent:
             url: ./how-to/extension-for-vscode.md
           - text: Design Azure Policy as Code workflows
             url: ./concepts/policy-as-code.md
-          - text: Implement Azure Policy as Code with GitHub
-            url: ./tutorials/policy-as-code-github.md
       - linkListType: deploy
         links:
           - text: Index of policy samples

articles/governance/policy/toc.yml

@@ -54,9 +54,6 @@
   - name: Route policy state change events
     displayName: event grid, subject, topic, subscription
     href: ./tutorials/route-state-change-events.md
-  - name: Implement Azure Policy as Code with GitHub
-    displayName: devops, infrastructure as code, iac, release, continuous, delivery, deploy
-    href: ./tutorials/policy-as-code-github.md
   - name: Implement Azure Policy with Azure DevOps
     displayName: devops, pipelines, releases
     href: ./tutorials/policy-devops-pipelines.md