about.md: fix little typos.

[learn-build-service-prod[bot]]

Learn Build status updates of commit 3b3a800:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
WSL/about.md	:white_check_mark:Succeeded	View

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[craigloewen-msft]

Looks good! Thanks for the great submission :)