Purpose

This pull request addresses the following issues:

• Fixed error: unrecognized arguments: --short-summary by changing the argument parser flag from --only-summary to short-summary. This error was encountered while using the README instructions for the Python command from the notebook folder.
• For better variable readability, update the get wiki article script.
• And updated the reference and help description from args.only_summary to args.short_summary.

Does this introduce a breaking change?

[ ] Yes
[X] No

Does this require changes to learn.microsoft.com docs?

[ ] Yes
[X] No

Type of change

[X] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[X] Refactoring (no functional changes, no API changes)
[ ] Documentation content changes
[ ] Other... Please describe: