[Guido's Gorgeous Lasagna] Update instructions.md (exercism#4132)

Clarified Docstring in task 5 per discussion in [forum](https://forum.exercism.org/t/guidos-gorgeous-lasagna-task-5-docstring-is-confusing/47323)

Author: BethanyG

exercises/concept/guidos-gorgeous-lasagna/.docs/instructions.md

@@ -80,12 +80,11 @@ def elapsed_time_in_minutes(number_of_layers, elapsed_bake_time):
     """Calculate the elapsed cooking time.
 
     :param number_of_layers: int - the number of layers in the lasagna.
-    :param elapsed_bake_time: int - elapsed cooking time.
-    :return: int - total time elapsed (in minutes) preparing and cooking.
+    :param elapsed_bake_time: int - time the lasagna has been baking in the oven.
+    :return: int - total time elapsed (in minutes) preparing and baking.
 
     This function takes two integers representing the number of lasagna layers and the
-    time already spent baking and calculates the total elapsed minutes spent cooking the
-    lasagna.
+    time already spent baking the lasagna. It calculates the total elapsed minutes spent cooking (preparing + baking).
     """
 ```