fix the vignette

Author: LittleBeannie

vignettes/articles/story-update-boundary.Rmd

@@ -250,7 +250,7 @@ We assume the observed events same as for the 1-sided example above.
 The updated design is
 ```{r}
 # Update spending fraction as above
-ustime <- c(sum(observed_data_ia$event) / max(x$analysis$event), 1)
+ustime <- c(240 / max(x$analysis$event), 1)
 
 gs_update_ahr(
   x = x,