errata: lowercase U in JSON numeric escapes

errata.html

@@ -140,6 +140,12 @@ pre {
     read "used as function parameters or results".
     (Thanks to Yang Yang 杨玚, 2016-04-18.)
   </p>
+
+  <p>
+    <b>p.107, ¶6</b>: in "JSON's <code>\U</code><i>hhhh</i> numeric escapes",
+    the <code>U</code> should be lowercase: <code>\u</code><i>hhhh</i>.
+    (Thanks to Kohei Marumoto (丸本耕平), 2016-09-23.)
+  </p>
  
   <p>
     <b>p.112</b>: Exercise 4.11 calls for a "CRUD" (create, read, update,