Convert economic model docs to PDF

Github doesn't render equations properly in notebook format

Author: al626

documentation/economic_model.ipynb

@@ -3,7 +3,7 @@
 ## Description
 
 AdaptER-Covid19 is an economic model intended to simulate the economic effects of Covid19. For more information, see
-the [model documentation](../../documentation/economic_model.ipynb)/
+the [model documentation](../../documentation/economic_model.pdf)/
 
 ## Compilation