Remove changelog section for dirname()

This mentionned only changes prior to PHP 7.0.0

Author: Girgias

reference/filesystem/functions/dirname.xml

@@ -103,30 +103,6 @@ dirname('C:\\'); // Will return 'C:\' on Windows and '.' on *nix systems.
   </caution>
  </refsect1>
 
- <refsect1 role="changelog">
-  &reftitle.changelog;
-  <para>
-   <informaltable>
-    <tgroup cols="2">
-     <thead>
-      <row>
-       <entry>&Version;</entry>
-       <entry>&Description;</entry>
-      </row>
-     </thead>
-     <tbody>
-      <row>
-       <entry>7.0.0</entry>
-       <entry>
-        Added the optional <parameter>levels</parameter> parameter.
-       </entry>
-      </row>
-     </tbody>
-    </tgroup>
-   </informaltable>
-  </para>
- </refsect1>
-
  <refsect1 role="examples">
   &reftitle.examples;
   <para>