For reasons I've never been able to understand many sites that have a separate subdomain for news and blogging about the site either do not have any kind of link on the blogging site back to the main site, or do but fail to make it obvious.

In this case the main site is https://www.soup.io/ and the submitted story is to their news/blog site at kitchen.soup.io. Go to the main site and it is clear there what they do.

There is actually a link to that at kitchen.soup.io, but it is easy to miss. It's the small red circled "soup" in the very upper right.