Typo fixes, plus a couple of code changes....

common/extensions/docs/static/overview.html

 <div id="pageData-title" class="pageData">Overview</div>
 <div id="pageData-showTOC" class="pageData">true</div>
 
 <p>
 Please read this page;
 it has vital information about the extension architecture.
 If you get bored or restless,
 take a break!
 We suggest bouncing between this page
 and tutorials
@@ skipping 61 matching lines @@
 <h3>Referring to files</h3>
 
 <p>
 You can put any file you like into an extension,
 but how do you use it?
 Usually,
 you can refer to the file using a relative URL,
 just as you would in an ordinary HTML page.
 Here's an example of referring to
 a file named <code>myimage.png</code>
-that's in a subdirectory named <code>images</code>.
+that's in a subfolder named <code>images</code>.
 </p>
 
 <pre>
 &lt;img <b>src="images/myimage.png"</b> style="width:auto; height:auto">
 </pre>
 
 <p>
 As you might notice while you use the Google Chrome debugger,
 every file in an extension is also accessible by an absolute URL like this:
 </p>
 
 <blockquote>
 <b>chrome-extension://</b><em>&lt;extensionID></em><b>/</b><em>&lt;pathToFile></em>
 </blockquote>
 
 <p>
 In that URL, the <em>&lt;extensionID></em> is a unique identifier
 that the extension system generates for each extension.
 You can see the IDs for all your loaded extensions
 by going to the URL <b>chrome://extensions/</b>.
 The <em>&lt;pathToFile></em> is the location of the file
-under the extension's top directory;
+under the extension's top folder;
 it's the same as the relative URL.
 </p>
 
 <p>
 For example, assume your extension has
 the ID <b>aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</b>
 and the files shown in the following figure:
 </p>
 
 <pre>
@@ skipping 255 matching lines @@
 <h2> Summary </h2>
 
 <p class="tbd">
 [
 PENDING: summarize, suggest where to go next. Probably:
 <a href="getstarted.html">Getting Started</a>,
 <a href="tut_debugging.html">Debugging</a>,
 <a href="devguide.html">Developer's Guide</a>.
 ]
 </p>