title: .gitignore doesn't stop changes being tracked in files
body: <p>Changes I make to a file that's within my <code>.gitignore</code> are being tracked by git.</p>
  
  <p>File structure:</p>
  
  <pre><code>.gitignore
  wp-config.php
  </code></pre>
  
  <p>Contents of <code>.gitignore</code>:</p>
  
  <pre><code>wp-config.php
  </code></pre>
  
  <p>When I change <code>wp-config.php</code>, and then run <code>git status</code> I see that it has been modified:</p>
  
  <pre><code>alex$ git status
  # On branch master
  # Changes not staged for commit:
  #   (use "git add &lt;file&gt;..." to update what will be committed)
  #   (use "git checkout -- &lt;file&gt;..." to discard changes in working directory)
  #
  #   modified:   wp-config.php
  #
  </code></pre>
  
  <p>How to I stop tracking this file? I thought putting it in <code>.gitignore</code> would be enough.</p>