Refer people with a Windows machine to cloud9.

We can't restrict this to just students with Unix machines. I'm gonna estimate that well over 50% of kids reading it will have Windows machines.
General spelling/grammar fixes.

Also reworded some things I thought were confusing and added a joke.
Fleshed out the TL;DR section.

I like the idea of a TL;DR, but if we're going to treat it like a true TL;DR section, shouldn't it be at the top? Otherwise, I'm cool with keeping it at the bottom, but we should called it "Summary" or "Recap" instead.
Changed the title
Merge pull request #1 from greysonp/master

Initial Fixes/Suggestions