Hardening of the Frontend docker image (#377)

* move the env-config script to a sub folder
* fix doc
* fix ports and ref to the official image
* add hardening to the docker-compose examples

frontend/scripts/start.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env sh
+
+ENV_CONFIG=/app/tmp/env-config.js
+
+if test -f $ENV_CONFIG; then
+    echo Config is locked
+else
+    echo Generate env-config script...
+    /usr/local/bin/env.sh
+    echo done
+    chmod 444 $ENV_CONFIG
+fi
+
+echo Starting nginx...
+nginx -g "daemon off;"