Please see:
https://docs.moodle.org/31/en/User_tours
Still present in all future versions of Moodle as far as I am aware.
Do know that it's on by default and there is a tour set to start/begin for all users .. including admin level user. What I don't know is what triggers the tour to begin/popup. Have seen some strange behavior and had some troubles in other areas of config in Moodle. When I finally hid the tours that were active, the strange behavlor in other areas stopped.
I know, off the wall and may/may not be related to the Dashboard but thought Dashboard was one of the 'stops' or 'items' in the tour.
'spirit of sharing', Ken