No, it doesn’t use the Discourse code and not connected to it in any way. It is a completely independent project, written in C++ and licensed under GPLv3.
I just found Discourse CLA to be well-written, so I want to apply its terms to contributors of my project. So, I am asking, if the the CLA text itself is copyrighted in some way (I didn’t see the copyright notice on its page, so…).