Clarify target of subordinate clause (#8320)

Merge pull request 8320

docs/_docs/structure.md

@@ -194,8 +194,8 @@ An overview of what each of these does:
       </td>
       <td>
         <p>
-          Every other directory and file except for those listed above—such as
-          <code>css</code> and <code>images</code> folders,
+          Except for the special cases listed above, every other directory and 
+          file—such as <code>css</code> and <code>images</code> folders,
           <code>favicon.ico</code> files, and so forth—will be copied verbatim
           to the generated site. There are plenty of <a href="/showcase/">sites
           already using Jekyll</a> if you’re curious to see how they’re laid