Docs and gkt versions

I would like to propose a new information on the docs, something like:
<note>
  <para>
    This function is only available when php-gtk is build using Gtk 2.12 
or a later version.
  </para>
</note>

So the user know that if the function needs a recent version of php-gtk. 
The php manual have this kind of info for every function.
Can I do this? Any ideas ?