Add extra CFU definition at top of index.rst.
Add extra CFU definition at top of index.rst.

Signed-off-by: Joey Bushagour <5b4986e288c8f7647a5f2f7db25a2849a443988d@google.com>

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