docs: Fixing formatting problem

Fixing problem (mismatched <div> tags) that caused the page text to be
obscured. See first comment for doc stage location.

bug: 31046432
Change-Id: I82227fd29764755885458c1c011db534325fcde3
diff --git a/docs/html/training/multiple-threads/define-runnable.jd b/docs/html/training/multiple-threads/define-runnable.jd
index 40853d3..84c7bdf 100644
--- a/docs/html/training/multiple-threads/define-runnable.jd
+++ b/docs/html/training/multiple-threads/define-runnable.jd
@@ -23,11 +23,10 @@
 <div class="download-box">
     <a href="{@docRoot}shareables/training/ThreadSample.zip" class="button">Download the sample</a>
     <p class="filename">ThreadSample.zip</p>
-</div>
-</div>
+</div> <!-- download-box -->
 
-</div>
-</div>
+</div> <!-- tb -->
+</div> <!-- tb-wrapper -->
 
 <p>
     This lesson shows you how to implement a {@link java.lang.Runnable} class, which runs the code