Update navigation.yml

Author: weizhi-lin

_data/navigation.yml

@@ -9,9 +9,12 @@ main:
   - title: "Publications"
     url: /publications/
 
-  - title: "Teaching & Mentoring"
+  - title: "Teaching"
     url: /teaching/
-
+    
+  - title: "Mentoring"
+    url: /mentoring/
+    
   - title: "Presentations"
     url: /presentations/