@dranzolin this is a good question.
WIki pages all include a 'Page History' with timestamps.
But I am not able to find a reference to timestamps for the syllabus.
This seems so obvious I'm interested to see if anyone has a solution.
We put minimal information in our syllabus page, and require faculty to upload an official syllabus document each semester.
The official document contains a timestamp, in case there is any question regarding whether or not the document has been updated. We have received good feedback from faculty on this, as it does not require them to learn HTML/CSS.