Vignette: clean up code

vignettes/using-the-lifeinsurancecontracts-package.Rmd

@@ -286,15 +286,16 @@ as it is created. It is, however, also possible to modify a contract later on,
 e.g. by stopping premium payments and converting it to a paid-up contract.
 
 ```{r SimpleExampleRiskConversionCode, eval=F}
-contract.L71U = contract.L71U$premiumWaiver(t = 3)
-contract.L71U$Values$reserves
+contract.L71U.prf = contract.L71U$premiumWaiver(t = 3)
+contract.L71U.prf$Values$reserves
 ```
 ```{r SimpleExampleRiskConversionOut, echo=F}
-contract.L71U = contract.L71U$premiumWaiver(t = 3)
-contract.L71U$Values$reserves %>% pander()
+contract.L71U.prf = contract.L71U$premiumWaiver(t = 3)
+contract.L71U.prf$Values$reserves %>% pander()
 ```
 
 
+
 ## Creating tables with various parameters
 
 When prototyping a new product or creating marketing material, it is often needed