Update README: highlight brew post-install steps (#1543)
Update README: highlight brew post-install steps (#1543)

I skimmed past the requires post-installation steps for Homebrew when walking though the README. 
Anecdotally, other devs noted the same issue.
sebhahn/pyenv,yyuu/pyenv,sebhahn/pyenv,pyenv/pyenv,yyuu/pyenv,pyenv/pyenv,pyenv/pyenv,sebhahn/pyenv