Add help content to a library
I think you need to get a *.CHM editor from the internet. There are free versions if you google them.
With that software you will be able to add extra contents to the helpfiles.
I have downloaded one and been able to make changes on the *.chm.
So you have to do it in 2 steps.
Add your library and make the changes to the Helpfiles.(C:\Program Files (x86)\3S Software\CoDeSys V2.3\Help)