Fix include path to reflection.h in documentation
Fix include path to reflection.h in documentation

There is a note in the documentation to `Reflection::GetRepeatedFieldRef()`
about file `net/proto2/public/reflection.h` which contains a definition of
`RepeatedFieldRef`. Since there are few places in code with rewrite of
`net...` path to `google/protobuf/...` it looks like the first one is a
legacy path and should be renamed to `google/protobuf` in documentation
as well.

google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf