meta-mchp-common: README: update repo init to fetch release tag

Update the repo init command to fetch the latest release tag for the
manifest file instead of the HEAD of active development branch (e.g
scarthgap)

Signed-off-by: Hari Prasath Gujulan Elango <hari.prasathge@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Author: gehariprasath

meta-mchp-common/README.md

@@ -59,7 +59,7 @@ To integrate this layer into your Yocto Project build environment:
     For the MPU layer:
 
       ```bash
-      repo init -u https://github.com/linux4microchip/meta-mchp-manifest.git -b scarthgap -m mpu/default.xml
+      repo init -u https://github.com/linux4microchip/meta-mchp-manifest.git -b refs/tags/linux4microchip-2025.04 -m mpu/default.xml
       ```
 
     For the PolarFire SoC layer: