Imported content contains xrefs to other upstream guides that are not in the downstream repo.

This task tracks the converting of those xrefs to links: to ensure that they render as expected.

Steps to complete on every Security topic:
Pre-req:
Make sure the downstream attribute

{url-quarkusio-guides} is set correctly in an observed attributes file. In the current architecture, the value is set in root../common/attributes.adoc as it is used by both up and downstream to render content.

`:url-quarkusio-guides: https://quarkus.io/version/{ProductVersion}/guides/`

1. Run a link checker on the transformed HTML output.
2. Identify the xrefs to upstream adoc files that are not imported downstream.
3. Convert `xref:<filename.adoc>[Label]` to `link:{url-quarkusio-guides}

filenameLabel]`.
4. Test on PV2.