Add Rivet by Indiana university

[Laisvunas]

Hi,

Rivet by Indiana university might be added to the list of CSS frameworks:

https://rivet.iu.edu/

https://rivet.iu.edu/about/

[troxler]

Thanks for the suggestion. It seems that this specifically targets at projects related to IU. Neither GitHub stars nor npm downloads suggest that this design system is used that much. Hence, I don't think this is interesting for a broader audience.