setup/terminal.html: Remove Cygwin reference from OS X instructions

Reported-by: Amy Brown <amyrhoda@gmail.com>
Merge pull request #354 from gvwilson/add-viana-to-team-page

Adding Alex Viana to the team roster
Merge pull request #349 from wking/os-x-no-cygwin

Remove reference to Cygwin under MacOS
Merge pull request #345 from gvwilson/book

Recent work on the instructor's guide.
Updated with final topics, link to GitHub README.md and my e-mail
Merge pull request #355 from mikej888/master

Updated to link to and be consistent with GitHub README.md