Remove erroneous extra <code> (#312)

Reviewers: Luke Chen, Bill Bejeck <bbejeck@apache.org>
diff --git a/27/design.html b/27/design.html
index 9e08b5f..a1e438e 100644
--- a/27/design.html
+++ b/27/design.html
@@ -453,7 +453,7 @@
     <p>
     Let's discuss a concrete example of such a stream. Say we have a topic containing user email addresses; every time a user updates their email address we send a message to this topic using their user id as the
     primary key. Now say we send the following messages over some time period for a user with id 123, each message corresponding to a change in email address (messages for other ids are omitted):
-    <pre class="line-numbers"><code class="language-text"><code>       123 => bill@microsoft.com
+    <pre class="line-numbers"><code class="language-text">       123 => bill@microsoft.com
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