Fix .dockstore.yml

[aofarrel]

This entry is currently not displaying correctly on Dockstore, likely due to the lack of ".wdl" in descriptor file path, resulting in the WDL not being found:

• 2.1.1
• Master

Older entries such as 2.1.0 are still working.

This PR should fix the issue on master and any subsequent releases. The addition of the authors field and the spacing adjustments are not strictly required.

[denis-yuen]

Upvoting, noticed this too