Update cmd2/argparse_custom.py

Improve docstring to make it more accurate

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: tleonhardt

cmd2/argparse_custom.py

@@ -388,8 +388,8 @@ def __init__(self, value: object, description: str | Sequence[Any], *args: Any)
         """CompletionItem Initializer.
 
         :param value: the value being tab completed
-        :param description: a string or list of descriptive data to display in the columns that follow
-                                 the completion value. If a list, the number of items in this list must equal
+        :param description: a string or sequence of descriptive data to display in the columns that follow
+                                 the completion value. If a sequence, the number of items in this sequence must equal
                                  the number of descriptive headers defined for the argument.
         :param args: args for str __init__
         """