Update docs for using qt-cmake

Author: DonLakeFlyer

docs/en/qgc-dev-guide/getting_started/index.md

@@ -137,9 +137,11 @@ Example commands to build a default QGC and run it afterwards:
 1. Configure:
 
    ```sh
-	cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Debug
+	/Qt/6.8.2/gcc_64/bin/qt-cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Debug
    ```
 
+   Change the directory for qt-cmake to match your install location for Qt and the kit you want to use.
+
 1. Build
 
    ```sh