added a comma

Author: cameraMeasurementTech

src/patterns.md

@@ -385,7 +385,7 @@ match slice {
     ["a", end @ ..] => println!("ends with: {:?}", end),
 
     // 'whole' is the entire slice and `last` is the final element
-    whole @ [.., last] => println!("the last element of {:?} is {}", whole, last)
+    whole @ [.., last] => println!("the last element of {:?} is {}", whole, last),
 
     rest => println!("{:?}", rest),
 }