README: Add Homebrew installation instructions
README: Add Homebrew installation instructions

https://github.com/Homebrew/homebrew/commit/b9463fc099d96a5a513ccb4733b7e5754206ba6e
bwall/HashPump,christophetd/HashPump,bwall/HashPump,0x0mar/HashPump,0x0mar/HashPump,christophetd/HashPump