Since it wasn't too obvious

Added a new line that makes it more obvious what command we want to run to prepare for branching.

Author: zg

guide/challenges/branches_arent_just_for_birds.html

@@ -69,6 +69,8 @@ <h2>GitHub Pages</h2>
       <code>http://githubusername.github.io/repositoryname</code>
 
       <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 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>
 
@@ -183,4 +185,4 @@ <h2>Tips</h2>
 
       </script>
     </body>
-</html>
+</html>