It now supports the output of an index file too.
And you can use the "/p [prefix]" switch to prefix the paths to the source HTML file with [prefix], so that you can place the textfile in a subdirectory (or parent directory) of the Docs directory.
When used in a parent directory, use:
When used in a subdirectory, use:chmgen.exe /p "Docs\" NSIScontents.txt
Else, just don't use the /p-switch.chmgen.exe /p "..\" NSIScontents.txt