add listing tags

Author: habibasorour

source/ch9_commonmistakes.ptx

@@ -63,6 +63,7 @@
         <p>
             A common mistake in Java is to forget that every statement must end with a semicolon (<c>;</c>).
         </p>
+        <listing xml:id="semicolon-error">
         <program language="java" interactive="activecode" line-numbers="yes">
             <code>
             // Histo.java
@@ -77,6 +78,7 @@
             }//End of class
         </code>
         </program>
+        </listing>
         <p>
             The error "';' expected" on line 7 of <c>Histo.java</c> means that a semicolon is missing at the end of the statement <c>Scanner data = null</c>. In Java, every statement must be terminated with a semicolon (<c>;</c>) to indicate its completion. The arrow points to <c>null</c> because that's where the compiler expected to find the semicolon.
         </p>