shell-support-warning: create package
By adding this warning it should be clearer to users that they are getting in to unsupported area and that they are on their own. That doesn't mean that they should not do it but rather that they should not request official support for it. They should rather use community channels.
Edit: I was also thinking about uci option to disable this but I rather decided that if you want to disable it you can just remove package which is easier to implement
implements turris/reforis/reforis#258 (closed).