docs(readme): clarify Postman recommendation with companion repo synopsis

- rename the Recommendations heading to link directly to Postman-PyPNMApps-API
- replace the minimal Postman note with a short synopsis of what the companion repo provides
- clarify that the Postman repo includes maintained collections, environments, and visualizers for PyPNM endpoint testing and analysis workflow validation - 2026-02-23 10:38:20

Author: mgarcia01752

README.md

@@ -219,10 +219,9 @@ Installed services and docs are available at the following URLs:
 | [FastAPI ReDoc](http://localhost:8000/redoc)      | [FastAPI ReDoc](http://localhost:8080/redoc)      |
 | [MkDocs docs](http://localhost:8001)              | [MkDocs docs](http://localhost:8081)              |
 
-## Recommendations
+## Recommendations - [Postman-PyPNMApps-API](https://github.com/PyPNMApps/Postman-PyPNMApps-API)
 
-Postman is a great tool for testing the FastAPI endpoints:
-- [Download Postman](https://www.postman.com/downloads/)
+The companion `Postman-PyPNMApps-API` repo provides a maintained Postman collection, environments, and Postman visualizers for PyPNM FastAPI endpoints. It is intended for quick endpoint testing, capture/analysis workflow validation, and operator-friendly response visualization (tables/graphs) without writing custom client code.
 
 ## Documentation