Revert "Update branches_arent_just_for_birds.html"

guide/challenges/branches_arent_just_for_birds.html

@@ -70,7 +70,7 @@ <h2>GitHub Pages</h2>
 
       <h2>Step: Create a branch</h2>
       <p>Let's start by creating a new branch on your fork for your contribution:</p>
-      <p><code>$ git checkout -b gh-pages</code></p>
+      <p><code>$ git checkout gh-pages</code></p>
       <p>When you create a branch, Git copies everything from the current
         branch you're on and places it in the branch you've requested.</p>