feat: add disclaimer for deep search (#1237)

Useful additions for the time being, some people are still on CDS 7 with
`@sap/cds-hana` for production while using `@cap-js/sqlite` for
development. In this scenario, deep search in production will not work,
while it does during development.

---------

Co-authored-by: René Jeglinsky <[email protected]>

Author: patricebender

guides/providing-services.md

@@ -383,6 +383,10 @@ Searches the `title` element only.
 
 ##### Extend Search to *Associated* Entities
 
+::: warning Node.js: Only w/ streamlined database services
+For Node.js projects, this feature is only available with the [streamlined `@cap-js/` database services](../releases/jun24#new-database-services-ga) (default with `@sap/cds` >= 8)
+:::
+
 ```cds
 @cds.search: { author }
 entity Books { ... }