improve grammar in "Alternate customization methods" docs

getting-started.html

@@ -556,7 +556,7 @@ img { max-width: none; }
 
     <div class="bs-callout bs-callout-info">
       <h4>Alternate customization methods</h4>
-      <p>While not recommended for folks new to Bootstrap, you may use one of two alternate methods for customization. The first is modifying the source .less files (making upgrades super difficult), and the second is mapping source LESS code to <a href="http://ruby.bvision.com/blog/please-stop-embedding-bootstrap-classes-in-your-html">your own classes via mixins</a>. For the time being, neither options are documented here.</p>
+      <p>While not recommended for folks new to Bootstrap, you may use one of two alternate methods for customization. The first is modifying the source .less files (making upgrades super difficult), and the second is mapping source LESS code to <a href="http://ruby.bvision.com/blog/please-stop-embedding-bootstrap-classes-in-your-html">your own classes via mixins</a>. For the time being, neither of those options are documented here.</p>
     </div>
 
     <h3>Removing potential bloat</h3>