Fix 404 issue with the reference docs

Due to an antora ordering issue, the reference docs on the latest GA from
the project site throws an HTTP 404.

See spring-projects/spring-framework#32083 for more details.

antora-playbook.yml

@@ -1,10 +1,11 @@
 antora:
   extensions:
   - '@springio/antora-extensions/partial-build-extension'
+  # atlas-extension must be before latest-version-extension so latest versions are applied to imported versions
+  - '@antora/atlas-extension'
   - require: '@springio/antora-extensions/latest-version-extension'
   - require: '@springio/antora-extensions/inject-collector-cache-config-extension'
   - '@antora/collector-extension'
-  - '@antora/atlas-extension'
   - require: '@springio/antora-extensions/root-component-extension'
     root_component_name: 'amqp'
   - '@springio/antora-extensions/static-page-extension'