add simple script to update all json scene files from their yaml versions

config/update-yaml-files.bash

+#!/bin/bash
+
+# (re-)generate json configs from yaml files.
+# This command requires yq, which can be installed in ubuntu using `snap install yq`.
+
+for FILENAME in config_scene*.yaml objects.yaml; do
+    yq eval -o=json $FILENAME > "${FILENAME%%.*}.json"
+done
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