Constellations project peer review AND a question about posting ipynb files

Hi everybody, please kindly review my project:

I have also a question. In the task description for the project it was written that I have to save exactly the ipynb file and then post it here for a review. However, I didn’t manage to upload it here, only png, jpeg etc. files are accepted. So I published it on github. Anyway, just for my future projects, I would like to know, how can I post an ipynb file here? Or a link to github is enough? I am quite confused about it, please help me.
Many thanks in advance!