Update lecture_6.md - updated LGs

src/lecture_6.md

@@ -149,9 +149,8 @@ Extended BZ (n-th band within n-th BZ):
 
     After this lecture you will be able to:
 
-    - describe how an insulating or conducting nature of a material is related to the material's electronic band structure.
-    - examine 1D and 2D electronic band structures and argue if you expect the corresponding material to be an insulator/semiconductor or a conductor.
-    - describe how the light absorption spectrum of a material may be understood through its band structure.
+    - examine 1D and 2D band structures and argue if you expect the corresponding material to be an insulator/semiconductor or a conductor.
+    - describe how the light absorption spectrum of a material relates to its band structure.
     
 ## Band structure