scripts/make-release: Add a simple help text for the script

Print a simple help text if the script has been called with the
wrong amount of parameters.

Message-Id: <20221128092555.37102-2-thuth@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

scripts/make-release

@@ -10,6 +10,12 @@
 # This work is licensed under the terms of the GNU GPLv2 or later.
 # See the COPYING file in the top-level directory.
 
+if [ $# -ne 2 ]; then
+    echo "Usage:"
+    echo " $0 gitrepo version"
+    exit 0
+fi
+
 src="$1"
 version="$2"
 destination=qemu-${version}