Fixed spelling mistakes

Aufgabe02.py

 def HeapSort(array):
-    '''Sort the array by using a max-heap.
+    '''Sorts the array by using a max-heap.
 
     Parameters
     ----------
@@ -49,7 +49,7 @@ def HeapSort(array):
     return sorted_array
 
 def InsertionSort(array):
-    '''Sort the array by inserting each element into an already sorted part of the array.
+    '''Sorts the array by inserting each element into an already sorted part of the array.
 
     Parameters
     ----------
@@ -73,7 +73,7 @@ def InsertionSort(array):
     return sorted_array
 
 def CountingSort(array, k=None):
-    '''Sort the array by counting the ocjence of each element in the array.
+    '''Sorts the array by counting the occurrence of each element in the array.
 
     Parameters
     ----------