As of Nucleus v3.2 plugins can provide a helppage with an overview of the plugins' functionality, the available skinvars and templatevars, where to get more info,...

The helppage will be accessible from the plugin overview in the admin area.

Basics

To provide a helppage, you'll need take these steps:

1. Create a subdirectory of the plugins directory, and name it pluginname if your plugin is NP_PluginName. Note that the name should be lowercase! This is actually the same directory as for the admin area.
2. In that directory, create a file called help.html. In this file you can document your plugin. This is a good template to start from:

   <h3>Plugin overview</h3>
   
   <p>The only purpose of this plugin is to show how the plugin helppages work</p>
   
   <h3>Installation</h3>
   
   <p>If you can read this you correctly installed the plugin :-)</p>
   
   <h3>SkinVars</h3>
   
   <p>Because this plugin is only a testcase it doesn't has any skinvars/templatevars 
   but suppose it would have:
   
   <ul><li><b><%HelpPageTestCase1%></b>: does something</li>
   <li><b><%HelpPageTestCase1(foobar)%></b>: does something else</li></ul></p>
   
   <h3>Support and Bug reports</h3>
   
   <p>For additional support and/or bug reports please use this forum thread:
   <a href="http://forum.nucleuscms.org/viewtopic.php?t=<TOPIC_ID_GOES_HERE>">
   http://forum.nucleuscms.org/viewtopic.php?t=<TOPIC_ID_GOES_HERE></a></p>
   
   <h3>Version History</h3>
   
   <ul><li>Version 0.1: initial testcaseversion</li>
   <li>Version 0.0: pre-initial version ;-)</li></ul>

3. Return a value larger than 0 for supportsFeature('HelpPage'):

   function supportsFeature($what) {
   	switch($what) {
   	case 'HelpPage':
   		return 1;
   	  default:
   		return 0;
   	}
     }