build.sh: minor change

live_exam_os/build.sh

@@ -12,7 +12,7 @@ export ARCH="amd64"
 
 helper() {
   echo "USAGE: $(basename "$0") envfile"
-  echo "  envfile            Path to an environment file containing the config to use"
+  echo "  envfile    path to an environment file containing the config to use when building the image"
   exit 1
 }