The about page currently has the following text describing our site:
Skeptics is a question and answer site for applying scientific skepticism. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers challenging unreferenced notable claims, pseudoscience and biased results.
This page is shown prominently to new users, and it should explain the most important aspects of our site and what this site is about. The citation requirement is probably the most important aspect of this site and it defines the purpose of this site, it should certainly be mentioned in the about text.
I'll propose one minimal example that adds it to this text, but maybe someone has a better idea on how to rewrite the about text.