Updated MNRL Submodule to compile on Apple M1 Processors as well as Updated Readme.md

[tjt7a]

This pull request updates the MNRL submodule so that VASim can be compiled and run on Apple's M1 silicon. Initial tests show significant speedups on M1-pro vs Intel's i7 or Xeon processors. It also updated the README.md and removed installation instructions for Windows, because it is not being tested on Windows.