Add documentation

Hi

I am very missing documentation for this module. There is no readme.txt inside the module, and the link to documentation on project page doesn't work. This: http://jamesarmes.net/plugins/drupal/button_field

Is there some option how to understand how this is working, what kind of rule could be created, and how to link this button with that rule?
I would like to use this module for changing (+1) of one cck field (number) in the node.
If I understand this correctly, this could be used as a replace of all behaviour - open node, changing value of cck field, save node.
Pressing the button could take over whole this process and the result will be changed number in the node.
So I very appreciate some info/suggestion/documentation how to start and how to do this.

Thanks a lot
Igor