At the moment, the Help menu item links to this forum, which is nice, but I do think it would be nice to have an in-built manual for common questions or advanced features. It could probably be in .chm format - perhaps take a look at AIMP's for example.
One way to accomplish this might be for it to be community-driven. Perhaps make a git repository where people can file issues and submit pull requests.
I do also think it would be helpful to keep a link to this forum prominent on the landing page of the help files.