[Geany] [plugins][geanygendoc] how to use geanygendoc ?

[ssm2017]

hello
im trying to use geanygendoc for php in geany 0.19.1

i have created a function like that :

function test ($a, $b) {
  return $a;
}

so im using the "tools" menu then "document generator" then "document
current symbol"
-> nothing happens

using "document all symbols"
-> nothing happens

i could see that using the right click mouse button, there is a menu
called "insert comments" and inside, there is "insert function
description"
that is giving me :
/*
 *
 * name: unknown
 * @param
 * @return
 */

cool, but i could use "snippets" for that, i would prefear to see :
/*
 *
 * name: test
 * @param $a
 * @return $a
 */

there is also "insert documentation comments" but nothing is happening
when using it.

so im not able to use geanygendoc

the doc is containing a list of config options and some example that i
can not understand on how to use them, i thought that it was "install
and play" :)

if someone could provide a quick help on how to use it please ?