Readme.md: git clone via HTTPS

Originally found by @jwfu here:
barryclark#413

Author: barryclark

README.md

@@ -49,7 +49,7 @@ Edit `/_posts/2014-3-3-Hello-World.md` to publish your first blog post. This [Ma
 ## Local Development
 
 1. Install Jekyll and plug-ins in one fell swoop. `gem install github-pages` This mirrors the plug-ins used by GitHub Pages on your local machine including Jekyll, Sass, etc.
-2. Clone down your fork `git clone git@github.com:yourusername/yourusername.github.io.git`
+2. Clone down your fork `git clone https://github.com/yourusername/yourusername.github.io.git`
 3. Serve the site and watch for markup/sass changes `jekyll serve`
 4. View your website at http://127.0.0.1:4000/
 5. Commit any changes and push everything to the master branch of your GitHub user repository. GitHub Pages will then rebuild and serve your website.