Add link to source map of uncompressed UMD bundle in Download section

Author: jgonggrijp

index.html

@@ -442,7 +442,10 @@ <h2>Downloads <i style="padding-left: 12px; font-size:12px;">(Right-click, and u
     <table>
       <tr>
         <td><a href="underscore.js">Development Version (1.10.0)</a></td>
-        <td><i>60kb, Uncompressed with Plentiful Comments</i></td>
+        <td>
+          <i>60kb, Uncompressed with Plentiful Comments</i>
+          &nbsp;<small>(<a href="underscore.js.map">Source Map</a>)</small>
+        </td>
       </tr>
       <tr>
         <td><a href="underscore-min.js">Production Version (1.10.0)</a></td>