Adding the note for the 917SoC matter cli

Author: chirag-silabs

sld248-matter-overview-guides/serial-port-communications.md

@@ -120,3 +120,5 @@ To run matter shell on the Silicon Labs Platform, refer to the [Software Require
       ./chip-tool doorlock read-event door-lock-alarm "node_id" "endpoint"
 
   **Note**: Type **help** in matterCli terminal for more information about supported features.
+
+  **Note**: For 917SoC ICD-enabled devices, only 5 UULP pins are supported. As a result, the matter shell is not functional with sleepy applications since they are not mapped to UULP pins. To enable the Matter shell for Sleepy 917SoC devices, the P37 pin must be pulled up. Additionally, the boards BRD2708A, BRD2911A, and BRD4343A have only 3 UULP GPIO pins, which prevents the shell from functioning. To make it work, users should repurpose existing UULP GPIO pins.