Grammatical fix in netcore.md

[zacharykeeping]

Correct a minor grammatical error - "it's" to "its".

[opbld33]

Docs Build status updates of commit 0e27a4a:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
Odata-docs/webapi/netcore.md	:white_check_mark:Succeeded	View

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