There are some freely distributed tools that can be added to Sonar, and there is a thread somewhere that describes the various tools - If nobody else offers the link, when I wake back up I will find it for you.
Anyways, there some project inventory type tools that folks have written and posted them to these forum.
For MY purposes, I usually create one or several documents with all sorts of notes and such.
I place these project notes into usually a Notepad text file, or a Word document, but whatever you are happy using would work. I DID look at the various tools/utilities offered by some of the forum members, but I am pleased that the way I maintain such notes works for me, use whatever works for you.
One of the benefits of my keeping such information in separate fashion/files, is that if my project gets corrupted, or whatever - ALL of my notes are still safe, because they live outside the project itself. I DO place them into a sub-folder within the project's project folder, called Project Notes. Wherever that project goes, those project notes always go with the project.
I sure hope you find something that meets your needs, with either something like what I describe above, OR maybe with one or more of the utilities others built for Sonar and placed in the forums for review and download.
Bob Bone