Change mg_http_upload API

examples/file-upload-multiple-posts/web_root/index.html

@@ -21,7 +21,7 @@
         in small chunks.
         <br/><br/>
         In this example, the JavaScript code on this page sends the chosen
-        file in 4K chunks using the <code>/upload</code> endpoint.
+        file in 2Kb chunks using the <code>/upload</code> endpoint.
         The uploaded file is stored in the <code>/tmp</code> directory by
         the helper API function <code>mg_http_upload()</code>
       </div>