errata: p.222, Ex 8.1

Change-Id: I09f345da8784cba8da2e9f4822bf38031adfc06b

errata.html

@@ -141,6 +141,13 @@ pre {
     (Thanks to Mitsuteru Sawa, 2015-12-07.)
   </p>
 
+  <p>
+    <b>p.222. Exercise 8.1</b>: the port numbers for <code>London</code>
+    and <code>Tokyo</code> should be swapped in the final command to
+    match the earlier commands.
+    (Thanks to Kiyoshi Kamishima, 2016-01-08.)
+  </p>
+
   <p>
     <b>p.347, Exercise 12.8</b>: for "like <code>json.Marshal</code>",
     read "like <code>json.Unmarshal</code>".