Update Junyang's user group

Author: junyang-zh

content/authors/Junyang Zhang/_index.md

@@ -71,7 +71,7 @@ highlight_name: false
 # Organizational groups that you belong to (for People widget)
 #   Set this to `[]` or comment out if you are not using People widget.
 user_groups:
-  - Professors
+  - Graduate Students
 ---
 <!-- 
 Nelson Bighetti is a professor of artificial intelligence at the Stanford AI Lab. His research interests include distributed robotics, mobile computing and programmable matter. He leads the Robotic Neurobiology group, which develops self-reconfiguring robots, systems of self-organizing robots, and mobile sensor networks.