read-the-docs generation is broken

[mbertrand]

Steps to Reproduce

Follow the steps here.

Expected Behavior

docs available at http://localhost:4000/

Actual Behavior

Error #1: 404 trying to get custom theme defined here in _config.yml:

remote_theme: pmarsceill/just-the-docs
markdown: kramdown

After removing these lines, got another error:

Liquid Exception: Liquid syntax error (line 530): 
Variable '{{< youtube ${videoId}' was not properly terminated with regexp: /\}\}/ in ckeditor/plugin.md