Pybullet, box2d installation; ModuleNotFoundError: No module named 'finrl.meta'

First of all, thank you for developing this beginner-friendly project.

I'd like to point out one issue:

1. Installation of Pybullet, box2d in the Finrl package requires previous installation of [Visual Studio](https://visualstudio.microsoft.com/ja/vs/community/) from Microsoft, and it took me roughly 15 minutes for the whole package to finish installing. Perhaps worth adding this to the installation guide to make life easier for others.

Look forward to your reply. Thank you! :)