Update format documentation (Closes #2158)

documentation.html

@@ -21,7 +21,7 @@
 <li><a href="#d3">Frequently Asked Questions</a></li>
 <li><a href="#d4">Supported sites</a></li>
 <li><a href="#d5">Proxy support</a></li>
-<li><a href="#d6">YouTube formats</a></li>
+<li><a href="#d6">Video formats</a></li>
 <li><a href="#d7">Output template</a></li>
 <li><a href="#d8">Configuration</a></li>
 </ul>
@@ -60,9 +60,9 @@ For a complete list, see the <a href="supportedsites.html">Supported sites</a> p
 
 <p>youtube-dl supports downloading videos through a proxy, by setting the <em>http_proxy</em> environment variable to the proxy URL, as in <code>http://proxy_machine_name:port/</code>.</p>
 
-<h1 id="d6">YouTube formats</h1>
+<h1 id="d6">YouTube Video</h1>
 
-<p>Using the -f option and other related options, you can specify the video format to be downloaded from YouTube. If you have an order of preference, specify the formats separating them with slashes: <code>-f 22/17/18</code>. Instead of keeping a video format table here, I will refer you to the <a href="http://en.wikipedia.org/wiki/YouTube#Quality_and_codecs">list of YouTube formats on Wikipedia</a>.</p>
+<p>Using the -f option and other related options, you can specify the video format to be downloaded. Add the <code>-F</code> option to see all valid formats. If you have an order of preference other than best quality, specify the formats separating them with slashes: <code>-f 22/17/18</code>. You can also pass in an extension, like <code>-f mp4/webm</code>.</p>
 
 <h1 id="d7">Output template</h1>