Added code example for ModPerl 2 (#357)

Author: randolf

articles/http-charset/index.en.html

@@ -105,6 +105,8 @@ <h2>Scripting the header</h2>
   <p><strong class="leadin">Perl.</strong> Output the correct header before any part of the actual page. After the last header, use a double
     linebreak, e.g.:<br />
     <code>print "Content-Type: text/html; charset=utf-8\n\n";</code></p>
+  <p><strong class="leadin">ModPerl 2.</strong> Set the correct header before sending any part of the actual page, e.g.:<br />
+    <code>$r->content_type('text/html; charset=utf-8');</code></p>
   <p><strong class="leadin">Python.</strong> Use the same solution as for Perl (except that you don't need a semicolon at the end).</p>
   <p><strong class="leadin">PHP.</strong> Use the <a class="print" href="http://www.php.net/header">header()</a> function before generating any content,
     e.g.: <br />