README.md: add note about bugfix in proj_accel_1.
README.md: add note about bugfix in proj_accel_1.

Signed-off-by: Tim Callahan <ea16a3c075a6a229c9a452aa4faba7441b41c040@google.com>

google/CFU-Playground,google/CFU-Playground,google/CFU-Playground,google/CFU-Playground