Thank you for this! I'm going to try it out on my iPad - for months I've been looking for a tileset editor I can use on it!
I guess the best place would be the github tracker. You can open a ticket at the issues if you find a bug or have a feature request. If you want to directly contribute with code you can also fork it and make a pr. Its open source so its truely yours :)
If you have made a demo map, you can save it as a json file and upload that to gist. Demo maps and screenshots can also help promote the software to more users too.
I am very thankful to everyone who brought it here on itch. It motivates me to pick it up more often and push it further :3 Thank you ❤