Samsung Galaxy S6 at odd times makes noise and light and then Docking message at top left. How can I get it to stop doing this?

[AC Question]

Samsung Galaxy S6 at odd times makes noise and light and then "Docking" message at top left.

This is not prompted by anything I do. It can be day or night. It suddenly just starts as if it's doing some kind of update. I don't know if this is an app or native to the Samsung. And I don't know how to make it go away when it happens, but I'd like it just to stop doing it.