Fix atlas-extension order

Fixes the following error from latest-version-extension:
    FATAL (antora): The latest-version-extension must be registered
    after the atlas-extension

antora-playbook.yml

@@ -1,10 +1,10 @@
 antora:
   extensions:
   - '@springio/antora-extensions/partial-build-extension'
+  - '@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: 'security'
   - '@springio/antora-extensions/static-page-extension'