README.md: add details to the Versioning section
README.md: add details to the Versioning section

lanniaoershi/protobuf-c,hongbinz/protobuf-c,y12uc231/protobuf-c,virqin/protobuf-c,Sannis/protobuf-c,pepsi7959/protobuf-c,hongbinz/protobuf-c,Sannis/protobuf-c,lanniaoershi/protobuf-c,koolhazz/protobuf-c,virqin/protobuf-c,tutu12777/protobuf-c,pepsi7959/protobuf-c,y12uc231/protobuf-c,hongbinz/protobuf-c,pepsi7959/protobuf-c,Sannis/protobuf-c,koolhazz/protobuf-c,virqin/protobuf-c,y12uc231/protobuf-c,lanniaoershi/protobuf-c,tutu12777/protobuf-c,koolhazz/protobuf-c,tutu12777/protobuf-c