add parameter

src/config.xml

@@ -2686,6 +2686,15 @@ EXTRA_PACKAGES=times
  the generated man pages. In case
  the manual section does not start with a number, the number 3 is prepended.
  The dot (.) at the beginning of the \c MAN_EXTENSION tag is optional.
+]]>
+      </docs>
+    </option>
+    <option type='string' id='MAN_SUBDIR' format='string' defval='man3' depends='GENERATE_MAN'>
+      <docs>
+<![CDATA[
+ The \c MAN_SUBDIR tag determines the name of the directory created within \c MAN_OUTPUT
+ in which the man pages are placed. If defaults to man followed by \c MAN_EXTENSION
+ with the initial . removed.
 ]]>
       </docs>
     </option>