Added guidance to avoid nested assemblies

Author: Christopher Tauchen

contributing_to_docs/doc_guidelines.adoc

@@ -257,6 +257,8 @@ The following examples include IDs that are unique to the "Configuring alert not
 == Writing assemblies
 An _assembly_ is a collection of modules that describes how to accomplish a user story.
 
+Avoid link:https://redhat-documentation.github.io/modular-docs/#nesting-assemblies[nesting assemblies] in other assembly files. You can create more complicated document structures by modifying the link:https://github.com/openshift/openshift-docs/tree/main/_topic_maps[topic maps].
+
 For more information about forming assemblies, see the
 link:https://redhat-documentation.github.io/modular-docs/#forming-assemblies[Red Hat modular docs reference guide] and the link:https://raw.githubusercontent.com/redhat-documentation/modular-docs/master/modular-docs-manual/files/TEMPLATE_ASSEMBLY_a-collection-of-modules.adoc[assembly template].