remove migrated lectures

Author: HumphreyYang

lectures/_toc.yml

@@ -38,8 +38,6 @@ parts:
 - caption: Introduction to Dynamics
   numbered: true
   chapters:
-  - file: scalar_dynam
-  - file: ar1_processes
   - file: finite_markov
   - file: inventory_dynamics
   - file: linear_models