fix comment for is_none

README.md

@@ -4018,7 +4018,7 @@ fn main() {
 
     book_hashmap.insert(1, "L'Allemagne Moderne");
 
-    if book_hashmap.get(&1).is_none() { // is_none() returns a bool: true if it's Some, false if it's None
+    if book_hashmap.get(&1).is_none() { // is_none() returns a bool: true if it's None, false if it's Some
         book_hashmap.insert(1, "Le Petit Prince");
     }