I don’t see an answer to this question here yet. Are you saying you have a site where you are hosting articles, and you want each article to have a topic in your forum? If that’s what you want, you can look at Embed Discourse comments on another website via Javascript.
If you are using WordPress as your main site, you also can use GitHub - discourse/wp-discourse: WordPress plugin that lets you use Discourse as the community engine for a WordPress blog which is quite powerful for integrating your WordPress site with Discourse.