Tom's June 8 afternoon edits of two Cagan lectures plus the table of contents file

Author: thomassargent30

lectures/_toc.yml

@@ -24,6 +24,7 @@ parts:
   - file: cons_smooth
   - file: equalizing_difference
   - file: cagan_ree
+  - file: cagan_adaptive
   - file: geom_series
 - caption: Probability and Distributions
   numbered: true