improve documentation

install-mpsd-software-environment.py

@@ -307,7 +307,7 @@ def main():
                     type=str,
                     nargs="+",
                     default="NONE",
-                    help="List of toolchains to install (use ALL to install all toolchains). If nothing is specified, list of available toolchains for the release would be shown after creating the environment.",
+                    help="List of toolchains to install (use '--toolchains ALL' to install all toolchains). If nothing is specified, list of available toolchains for the release would be shown after creating the environment.",
                 )
                 subp.add_argument(
                     "--enable-build-cache",