Fix bad apstrophe under mirrored mode networking section

[krishnacx]

Fix bad apostrophe under networking section

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

Learn Build status updates of commit 63778a1:

:white_check_mark: Validation status: passed

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

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[krishnacx]

Fixes https://github.com/MicrosoftDocs/WSL/issues/1869

[krishnacx]

@mattwojo Kindly review