Fix typo in TaskContinuationOptions.xml

[cmorgan-osi]

Summary

Describe your changes here.

Fixes #Issue_Number (if available)

[ghost]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[opbld31]

Docs Build status updates of commit a8de8a2:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Threading.Tasks/TaskContinuationOptions.xml	✅Succeeded	View

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[ghost]

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Issue Details

---

Summary

Describe your changes here.

Fixes #Issue_Number (if available)

Author:	cmorgan-osi
Assignees:	-
Labels:	area-System.Threading.Tasks
Milestone:	-