Did you follow this Howto? Embedding Discourse Comments via Javascript
Make sure that you created an embeddable host in Discourse for doc.test.com and that the URLs in the JavaScript you embedded are correct and, in your case, use HTTPS.
It would be easier to help if we knew the actual URLs of your site. And did you change the error message you posted in any way? Because there is a whitespace in the URLs (https ://discourse.example.com).