Typo in appendix's circular buffer example

• https://gitlab.mpi-sws.org/jeehoon.kang/sra-gps/commit/36717b1ae89ff2fe51bd0255be2a1c6982aa5fa6 In short, "ri = 0, wi = 0, b = 0" -> "ri = 0, wi = 1, b = 2"

• I tried to make a merge request, but it seems I cannot make a cross-domain one (from jeehoon.kang to FP). So I just make an issue.