Fix capitalization in a static_assert message
Fix capitalization in a static_assert message

Summary: The other one has a capital T, make this one as well.

Reviewed By: tekknolagi

Differential Revision: D36527903

fbshipit-source-id: 5f8c1296bff92ef556b33254e0ed691c62a290fb

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly