Update split_into_first_and_last_name

Fix the return signature to reflect the List[str] return value, instead of `None`

Author: TarmacDenter

README.md

@@ -571,7 +571,7 @@ print(name)  # ['Ryan', 'McDermott']
 
 **Good:**
 ```python
-def split_into_first_and_last_name(name: str) -> None:
+def split_into_first_and_last_name(name: str) -> list:
     return name.split()
 
 name = 'Ryan McDermott'