[PR] [DOCS] Fix untyped typo
[PR] [DOCS] Fix untyped typo

Summary:
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Pull Request resolved: https://github.com/facebook/flow/pull/8437

Reviewed By: panagosg7

Differential Revision: D22503499

Pulled By: mroch

fbshipit-source-id: 8d99a3a20da4a2acf8417dd33b4d2e289988ca46

mroch/flow,facebook/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow