Courses page should say who the instructors are

[SethTisue]

https://docs.scala-lang.org/online-courses.html

This came up on Discord today — someone was hoping to take a class taught by Martin, and the web page gave them the impression that the classes were probably taught by someone else (because if Martin's the instructor, surely the page would say so? there is an instructor picture on the page but it's a picture of Julien)

I think it is a major selling point of Martin's courses that he is the instructor, and it should be foregrounded — at least by including the instructor names on all courses, and probably also by including at least one actual picture of Martin.