try.docopt.org is down

[nkakouros]

Visiting docopt.org and clicking the [Try docopt in your browser](http://try.docopt.org/) link, results in an error:

[keleshev]

Heroku closed its free tier, that's why. I think the solution is to use a JavaScript port instead and run it without a back-end as a github page, similar to docopt.org.