Add script that uses Docker image to update Bikeshed cache

update-bikeshed-cache-docker.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# Abort on error
+set -e
+# Echo commands
+set -x
+
+function cleanup() {
+  docker rm -v bikeshed-tmp
+}
+
+BIKESHED_ROOT=/usr/local/lib/python3.8/site-packages/bikeshed
+
+docker build -t bikeshed docker/bikeshed --no-cache
+docker create --name bikeshed-tmp bikeshed
+trap cleanup EXIT
+
+rm -r .bikeshed-include
+rm -r .spec-data
+
+docker cp bikeshed-tmp:"${BIKESHED_ROOT}"/boilerplate/webauthn .bikeshed-include
+docker cp bikeshed-tmp:"${BIKESHED_ROOT}"/spec-data .spec-data
+
+echo "Now be sure to run:"
+echo " git add .spec-data/ .bikeshed-include/"
+echo ""