move examples to correct locations

doc/PROTOCOL-HTTP2.md

doc/grpc-auth-support.md

examples/README.md

examples/cpp/README.md

examples/cpp/cpptutorial.md

examples/cpp/helloworld/Makefile

examples/cpp/helloworld/README.md

examples/cpp/helloworld/greeter_async_client.cc

examples/cpp/helloworld/greeter_async_server.cc

examples/cpp/helloworld/greeter_client.cc

examples/cpp/helloworld/greeter_server.cc

examples/cpp/route_guide/Makefile

examples/cpp/route_guide/helper.cc

examples/cpp/route_guide/helper.h

examples/cpp/route_guide/route_guide_client.cc

examples/cpp/route_guide/route_guide_db.json

examples/cpp/route_guide/route_guide_server.cc

examples/csharp/.gitignore

examples/csharp/.nuget/packages.config

examples/csharp/Greeter.sln