Update summary-stats.qmd

update the title as per issue and add in the 4 quantiles

SAS/summary-stats.qmd

@@ -1,10 +1,11 @@
 ---
-title: "Deriving Quantiles or Percentiles in SAS"
+title: "Calculating Quantiles (percentiles) in SAS"
 ---
 
 Percentiles can be calculated in SAS using the UNIVARIATE procedure. The procedure has the option `PCTLDEF` which allows for five different percentile definitions to be used. The default is `PCTLDEF=5`, which uses the empirical distribution function to find percentiles.
 
 This is how the 25th and 40th percentiles of `aval` in the dataset `adlb` could be calculated, using the default option for `PCTLDEF`.
+For quantiles, Q1= 25%, Q2=50%, Q3 = 75%, Q4=100%.
 
 ```{r, eval=FALSE}
 proc univariate data=adlb;