Please, update installation instructions for windows. #92

I had some problems installing gcld3 on windows (python 3.8). Simple pip install gcld3 didn't do the trick. But I've found a way to install it.

1. install vcpkg: https://vcpkg.io/en/getting-started.html.
2. use vcpkg to install protobuf: https://github.com/protocolbuffers/protobuf/blob/main/src/README.md

>vcpkg install protobuf protobuf:x64-windows

3. add a folder with protoc.exe to PATH environment variable. It should be located in \installed\x64-windows\tools\protobuf inside vcpkg folder
4. locate port_def.inc file. It should be in \installed\x64-windows\include\google\protobuf folder inside vcpkg installation
5. set INCLUDE variable to a folder, that contains google/protobuf/port_def.inc. \installed\x64-windows\include\ inside vcpkg installation.

set INCLUDE=[...]\vcpkg\installed\x64-windows\include

7. locate libprotobuf.lib file. It should be in \installed\x64-windows\lib inside vcpkg folder.
8. set LIB environment variable to that location.

set LIB=[...]\vcpkg\installed\x64-windows\lib

9. (if issue Installing on windows requires 'protobuf.lib' file that does not exist #91 not fixed) copy libprotobuf.lib to protobuf.lib
10. run

pip install gcld3

11. and.. there still some issues with installed gcld3...