Add a project
The catalog is assembled from public sources, which means anything not listed there is simply invisible to it. This form is the way in.
Submissions are reviewed by a person before anything is published. That is slower than an instant listing and it is the reason the catalog is worth reading.
Adding a GitHub or X link is worth doing. Those are what the catalog uses to tell an active project from an abandoned one, so an entry without them is more likely to be flagged as quiet later.