VISA scanner utility details added

Author: prathameshnium

docs/User_Manual.md

@@ -105,6 +105,8 @@ python run_pica.py
 
 Automatically launched upon startup (and accessible within modules), this utility scans for connected hardware. It uses `ResourceManager.list_resources()` to find devices and sends a standard ``*IDN?`` query to verify communication. This allows users to verify their hardware configuration before starting any experiment.
 
+In the main PICA launcher, the VISA/GPIB scanner is configured to execute automatically at application startup. This design choice is motivated by the fact that initiating a measurement without first verifying the instrument connection is highly likely to fail and may result in non-informative error messages, such as a VISA connection timeout.
+
 <p align="center">
   <img src="../pica/assets/Images/screenshots/01_GPIB_Scanner.png" alt="GPIB Scanner" width="300">
   <br>