docs(own-and-return): add commas

subjects/own-and-return/README.md

@@ -6,8 +6,8 @@ Create a struct `Film` that has one field `name` of type `String`.
 
 Create the following two functions:
 
-- Create a function `take_film_name` it will return the name and consume the film (you should not be able to reuse it after you passed it to the function).
-- Create a function `read_film_name` it will return the name without consuming the film (you can call the function multiple times with the same argument).
+- Create a function `take_film_name`, it will return the name and consume the film (you should not be able to reuse it after you passed it to the function).
+- Create a function `read_film_name`, it will return the name without consuming the film (you can call the function multiple times with the same argument).
 
 ### Expected functions