Make a note that !== did not exist until 4.0.0-RC2

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@33452 c90b9560-bf6c-de11-be94-00142212c4b1

functions/dir.xml

@@ -141,6 +141,7 @@ $d->close();
      <example>
       <title>List all files in the current directory</title>
       <programlisting role="php">
+// Note that !== did not exist until 4.0.0-RC2
 &lt;?php
 $handle=opendir('.');
 echo "Directory handle: $handle\n";