Fix syntax issue in c++ cuda api note (#48434)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/48434
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D25173692
Pulled By: glaringlee
fbshipit-source-id: bbd6fa7615200bf1eaea731a4ed251d423412593
