docs(files): expose adaptive handbook topics

README.md

@@ -137,6 +137,8 @@ manual interoperability testing.
 
 Connector and collaboration ownership boundaries are documented in
 `docs/CONNECTOR_BOUNDARY.md` and `docs/DOCUMENT_COLLABORATION_BOUNDARY.md`.
+The role-adaptive user, administration, integration, and operator guide is the
+[Files handbook](docs/FILES_HANDBOOK.md).
 
 ZIP uploads are processed without buffering the whole archive in memory. The API
 spools incoming ZIP request bodies to a bounded temporary file, then extracts