Fix typo in readme and continue to tweak local dev setup header

Author: ajpiano

README.md

@@ -58,10 +58,10 @@ attribution:
 
 The entire site is managed via [this Git repository](https://github.com/jquery/learn.jquery.com).  If you'd like to contribute new articles, make edits to existing content, or work on the site itself, the first thing you'll need is a [fork](http://help.github.com/fork-a-repo/). When you have changes you'd like to have reviewed for integration into the site, submit a [pull request](http://help.github.com/send-pull-requests/).
 
-If you're unfamiliary with Git, you can still contribute by editing files directly via [GitHub's in-browser editor](https://github.com/blog/905-edit-like-an-ace). But you won't be able to create new content, and you'll still need a GitHub account and a fork of this repository. So we encourage you to [learn how to use Git and GitHub](http://help.github.com/); it'll probably pretty useful no matter what.
+If you're unfamiliar with Git, you can still contribute by editing files directly via [GitHub's in-browser editor](https://github.com/blog/905-edit-like-an-ace). But you won't be able to create new content, and you'll still need a GitHub account and a fork of this repository. So we encourage you to [learn how to use Git and GitHub](http://help.github.com/); it'll probably pretty useful no matter what.
 
 
-## How Do I Preview This Project Locally?
+## How Do I Set Up a Local Development and Preview Environment?
 
 *This project requires Ruby >= 1.9 and [Bundler](http://gembundler.com/). If you don't already have a Ruby development environment, please see the corresponding section below.*