I did nothing and got added (I was not even aware of it until a few days ago) I think they manually add sites when they fit in their categories
But judging by their activity I think they will add your site if you ask and provide a description for it
We find and add most of the listed sites ourselves, whether it be through looking at the activity feed, tag searching or otherwise - we then gather these together and update periodically when we have a decent amount of sites ready.
Asking us to look at your site is fine too, though! If we think you have a decent enough amount of content we’ll find a place to add you. We write the descriptions by ourselves to try to keep Districts unbiased. Apologies for the late reply.
i like yours as well! <3