As per my comments, I think making a simple HTML page to serve as help documentation would be the easiest solution. Python Add Ins are fairly limited with pop up options. The HTML page wouldn't need to be hosted on a web server and can just be included in the install directory of the Add In and use relative paths to open this when the onClick() method is invoked.
The HTML doc can easily be opened using the builtin webbrowser module. So if you have a structure like this:
Your_AddIn_Name
\install
Your_AddIn_Name.py
help.html
You can open your help.html file in a web browser by adding this to your onClick() method:
# Your_AddIn_Name.py
import webbrowser
# code...
class SomeToolClass(object):
# code...
def onClick(self):
webbrowser.open('help.html')
onClick()method, you can use the builtin webbrowser module to call the HTML file:webbrowser.open(r'path\to\your\help_page.html'). If you package this up in theinstallfolder where the script resides, it is very easy to make it find it from the relative path.