[ViPPET] docs: refactor visual-pipeline user guide into consolidated structure

tools/visual-pipeline-and-platform-evaluation-tool/docs/user-guide/api-reference.md

@@ -1,5 +1,18 @@
 # API Reference
 
+The Visual Pipeline and Platform Evaluation Tool exposes a REST API that can be accessed directly by automation scripts
+or through the UI. The API documentation is available via Swagger UI.
+
+## Accessing the API
+
+Once the application is running, access the API documentation at:
+
+- `http://localhost/api/v1/docs`
+
+The Swagger UI provides an interactive interface for exploring and testing the API endpoints.
+
+## API Documentation Format
+
 <!--hide_directive```{eval-rst}
 .. swagger-plugin:: ./_assets/vippet.json
 ```hide_directive-->