bot-status.py: Cleaup tags for offline bots

In the grand tradition of HTML, it works fine
without them but might as well be correct.

Change-Id: I2dea61fcf3c8ddb3fe46aa6e483127a0cb717541
diff --git a/monitor/bot-status.py b/monitor/bot-status.py
index 0a3bf27..11e725f 100755
--- a/monitor/bot-status.py
+++ b/monitor/bot-status.py
@@ -170,7 +170,7 @@
         try:
           status = bots_status[(base_url, bot['name'])]
         except KeyError:
-          temp.write("  <td>{} is offline!</td>".format(bot['name']))
+          temp.write("  <td>{} is offline!</td>\n</tr>\n".format(bot['name']))
           continue
 
         found_failure |= status['fail']