List of dependencies?

It seems TBB is a hard dependency? It would be nice to know that on the front-page and/or README. 

Or perhaps I have missed something -- I wanted to use this project on an embedded micro-controller, but I don't think TBB would run there? Just looking to clarify whether it is even possible to use `cpp.react` without TBB (sequential only?), or if TBB should work on non-Intel platforms?