docs: update Azure Pipelines link to learn.microsoft.com (#24456)

## Summary

- Updates the Azure Pipelines link in the "Third-party platforms"
section of `content/manuals/docker-hub/usage/pulls.md`
- Replaces the deprecated `docs.microsoft.com` domain with
`learn.microsoft.com` (Microsoft's current documentation domain)
- Removes the stale `#sep-docreg` anchor, which no longer exists on the
current page and causes users to land at the wrong location

Closes #24437

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Docker Docs Agent <agent@docker-docs-harness.local>

Author: dvdksn

content/manuals/docker-hub/usage/pulls.md

@@ -119,7 +119,7 @@ If you're using any third-party platforms, follow your provider’s instructions
 - [Artifactory](https://www.jfrog.com/confluence/display/JFROG/Advanced+Settings#AdvancedSettings-RemoteCredentials)
 - [AWS CodeBuild](https://aws.amazon.com/blogs/devops/how-to-use-docker-images-from-a-private-registry-in-aws-codebuild-for-your-build-environment/)
 - [AWS ECS/Fargate](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/private-auth.html)
-- [Azure Pipelines](https://docs.microsoft.com/en-us/azure/devops/pipelines/library/service-endpoints?view=azure-devops&tabs=yaml#sep-docreg)
+- [Azure Pipelines](https://learn.microsoft.com/en-us/azure/devops/pipelines/library/service-endpoints?view=azure-devops&tabs=yaml)
 - [Chipper CI](https://docs.chipperci.com/builds/docker/#rate-limit-auth)
 - [CircleCI](https://circleci.com/docs/guides/execution-managed/private-images/)
 - [Codefresh](https://codefresh.io/docs/docs/docker-registries/external-docker-registries/docker-hub/)