docs: 📜 Clarify that filtering is only on main entity

Author: erlendellefsen

CLAUDE.md

@@ -55,7 +55,7 @@ Documentation is built using DocFX and deployed to GitHub Pages. The documentati
    - Base controller for JSON:API endpoints
    - Provides methods: `JsonApiOk()`, `JsonApiOkAsync()`, `JsonApiCreated()`, `JsonApiNotFound()`, etc.
    - Handles query parameter parsing and response formatting
-   - Automatically applies filtering, sorting, pagination, and includes (relationships are auto-applied based on query parameters)
+   - Automatically applies filtering, sorting, pagination, and includes (filtering applies to main entity; includes load related resources)
 
 2. **JsonApiMapper** (`Mapping/JsonApiMapper.cs`)
    - Core mapper for converting entities to JSON:API resource structures

docs/docs/querying.md

@@ -65,6 +65,12 @@ With this request, the toolkit will:
 - Return the first 10 results.
 - Include related author and reviews data in the response.
 
+**Note:** Filtering applies only to the main resource type (books in this example). The `include` parameter controls which related resources are loaded in the response, but does not affect which main resources are returned by the filters.
+
+## Limitations
+
+- **Filtering on included resources**: Filters only apply to the main resource type. To filter based on related entity properties, structure your query at the main entity level or use custom controller logic.
+
 ## Missing Attributes in JSON:API Responses
 
 When using our JSON:API implementation, you might notice that certain properties—such as `CompanyTenantId`—are not included in the API responses. This is because the default attribute mapping logic intentionally excludes any property that ends with "`Id`" (other than the primary `Id`).