fixed broken link
Currently, Microsoft distributes site is broken linked. Instead use of WayBack Machine.
Added to ePub generates.
@@ -13,7 +13,8 @@ The documentation is created using Sphinx (A popular tool written in Python)
(4) Then run : python _mapping.py
-(5) To generate CHM file, Use Microsoft Help Workshop : https://www.microsoft.com/en-us/download/details.aspx?id=21138
+(5) To generate CHM file, Use Microsoft Help Workshop (from WayBack Machine): https://web.archive.org/web/20200918004813/http://download.microsoft.com/download/0/A/9/0A939EF6-E31C-430F-A3DF-DFAE7960D564/htmlhelp.exe
(6) To generate PDF file, Use Lyx (https://www.lyx.org/Download) and MiKTEX (https://miktex.org/download)
+(7) To generate ePub file (optional), running make.bat epub
