Dumux handbook should contain a building date and a git-version-hashmark on titlepage
While it is also possible to provide to provide meta-information on the webpage, it would be nice to have them also inside the pdf-file. It should not be that hard to add it, I think \today would do it for the date. Think also about to include branch or tag if available. Maybe a small script could generate some latex-output to handle over information. Or there is also latex-package like gitinfo2.