Update influenza-like-illness-analysis.Rmd

module3/exo1/influenza-like-illness-analysis.Rmd

@@ -25,6 +25,7 @@ The data on the incidence of influenza-like illness are available from the Web s
 ```{r}
 data_url = "http://www.sentiweb.fr/datasets/incidence-PAY-3.csv"
 ```
+If the local file does not exist, download the data and put them into the local file
 ```{r}	
 data_file = "syndrome-grippal.csv"	
 if (!file.exists(data_file)) {