errata: p.48 ReadByte

Change-Id: Ieab060609d92e9ac07c70406eabf488298ee5e9e

errata.html

@@ -60,6 +60,13 @@ pre {
     (Thanks to Peter Jurgensen, 2015-11-21.)
   </p>
 
+  <p>
+    <b>p.48</b>: <code>f.ReadByte()</code> serves as an
+    example of a reference to <code>f</code>, but <code>*os.File</code> has no such
+    method.  For <code>ReadByte</code>, read <code>Stat</code>, four times.
+    (Thanks to Peter Olsen, 2015-01-06.)
+  </p>
+
   <p>
     <b>p.52, ¶2</b>: For "an synonym", read "a synonym", twice.
     (Corrected in the second printing.)