Update description of experimental APIs. (history is NOT experimental!)

chrome/common/extensions/docs/static/api_index.html

 <div id="pageData-name" class="pageData">chrome.* APIs</div>
 <div id="pageData-showTOC" class="pageData">true</div>
 
 <p>
 Google Chrome provides APIs such as
 <code>chrome.bookmarks</code> and <code>chrome.tab</code>
 so that extensions can interact with the browser.
 </p>
 
 <h2 id="supported">Supported APIs</h2>
 
 <p>
 Here are the supported chrome.* APIs:
 </p>
 
 <ul>
   <li jsselect="stableAPIs();"><a jsvalues=".href: $this + '.html'" jscontent="$this" href="bookmarks.html" js>bookmarks</a></li>
 </ul>
 
 <h2 id="experimental">Experimental APIs</h2>
 
 <p>
-Google Chrome also has some
+Google Chrome also has
 <a href="experimental.html">experimental APIs</a>,
-which give you access to
-functionality such as process information and history.
+some of which will become supported APIs
+in future releases of Chrome.
 </p>
 
 <h2 id="conventions">API conventions</h2>
 
 <p>
 Unless the doc says otherwise,
 methods in the chrome.* APIs are <b>asynchronous</b>:
 they return immediately,
 without waiting for the operation to finish.
 If you need to know the outcome of an operation,
 then you pass a callback function into the method.
 For more information, watch this video:
 </p>
 
 <p>
 <iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/bmxr75CV36A?rel=0" frameborder="0" allowfullscreen></iframe>
 </p>