typo + clarify in vignette "multilevel"

Author: etiennebacher

vignettes/multilevel.Rmd

@@ -45,7 +45,7 @@ if (!requireNamespace("ggplot2", quietly = TRUE) ||
 ## Data
 
 Imagine we have an experiment in which **10 individuals** completed a task with
-**100 trials**. For each trial - there will 1000 trials (10 * 1000) in total -
+**100 trials**. For each of the 1000 trials (10 * 100) in total,
 we measured two things, **V1** and **V2**, and we are interested in
 **investigating the link between these two variables**.