Merge branch 'fix-5321' of https://github.com/mpilgrem/stack into stable

Author: snoyberg

doc/README.md

@@ -17,6 +17,9 @@ It features:
 
 #### How to install
 
+Stack can be installed on most Unix-like (Un*x) operating systems, including
+macOS, and on Windows.
+
 For most Un*x operating systems, the easiest way to install is to run:
 
     curl -sSL https://get.haskellstack.org/ | sh