Added some info on how to use FFEA correctly for beginners

[Changqing Zheng]

For windows beginners, I really recommend use WSL1 with Ubuntu18.04. I used WSL2 with Ubuntu18.04 or CentOS8, there are many mistakes. Such as, pymol, matplotlab and LibGLU and so on.

#For Mac beginners, (I don’t know, other people should add more information)