add C++ to `Language-Specific` section

[blockspacer]

add C++ to Language-Specific section

Examples:

CMake script to find GRPC
https://github.com/mattpaletta/foobar-social/blob/master/news_feed/build/cmake/FindGRPC.cmake

C++ grpc microservice example
https://github.com/lucperkins/colossus/blob/main/userinfo/userinfo-server.cc