Add a section for PyXLL

Author: tonyroberts

content/pages/index.md

@@ -5,7 +5,7 @@ url:
 This site contains pointers to the best information available about working with [Excel](https://products.office.com/en-us/excel) files in the [Python](http://www.python.org/) programming language.
 
 
-## The Packages
+## Reading and Writing Excel Files
 
 There are python packages available to work with Excel files that will run on any Python platform and that do not require either Windows or Excel to be used. They are fast, reliable and open source:
 
@@ -40,6 +40,17 @@ This package collects utilities that require both `xlrd` and `xlwt`, including t
 
 [Download](http://pypi.python.org/pypi/xlutils) | [Documentation](http://xlutils.readthedocs.io/en/latest/) | [GitHub](https://github.com/python-excel/xlutils)
 
+## Writing Excel Add-Ins
+
+The following products can be used to write Excel add-ins in Python.
+
+### PyXLL
+
+PyXLL is a commercial product that enables writing Excel add-ins in Python with no VBA. Python functions can be exposed as
+worksheet functions (UDFs), macros, menus and ribbon tool bars.
+
+[Homepage](https://www.pyxll.com) | [Features](https://www.pyxll.com/features.html) | [Documentation](https://www.pyxll.com/docs/index.html) | [Download](https://www.pyxll.com/download.html)
+
 ## The Mailing List / Discussion Group
 
 There is a [Google Group](http://groups.google.com/group/python-excel) dedicated to working with Excel files in Python, including the libraries listed above along with manipulating the Excel application via COM.