Revert "remove module in xref for adoc in module"

This reverts commit 094d297.

Author: NickLarsenNZ

modules/concepts/pages/stackable_resource_requests.adoc

@@ -2,7 +2,7 @@
 // WARNING: do not add headers here as they can break the structure of pages
 // that include this file.
 Stackable operators handle resource requests in a sligtly different manner than Kubernetes.
-Resource requests are defined on xref:stacklet.adoc#roles[role] or xref:stacklet.adoc#role-groups[role group] level.
+Resource requests are defined on xref:concepts:stacklet.adoc#roles[role] or xref:concepts:stacklet.adoc#role-groups[role group] level.
 On a role level this means that by default, all workers will use the same resource requests and limits.
 This can be further specified on role group level (which takes priority to the role level) to apply different resources.