move geom_series back to Foundations

Author: mmcky

lectures/_toc.yml

@@ -18,6 +18,7 @@ parts:
   - file: intro_supply_demand
   - file: linear_equations
   - file: complex_and_trig
+  - file: geom_series
 - caption: "Linear Dynamics: Finite Horizons"
   numbered: true
   chapters:
@@ -29,7 +30,6 @@ parts:
 - caption: "Linear Dynamics: Infinite Horizons"
   numbered: true
   chapters:
-  - file: geom_series
   - file: eigen_I
 - caption: Probability and Distributions
   numbered: true