Regarding logo, there is no strict guidelines, except making sure that you don’t change the original color / form. You can find colored or black white variants on our Brand Asset Page.
Regarding copyright, the image of our blog posts should be attributed to Bettina Steinbrecher (https://twitter.com/made_by_betty). No explicit attribution needed for the ReScript logo when used in blog posts and other writings (it’s essentially owned by “The ReScript Project”).
Good questions though, we will add more visible license information for our logo files soon.