[docs] Fix argument type of torch.masked_select (#30385)
Summary:
This should be `BoolTensor`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30385
Differential Revision: D19698414
Pulled By: ezyang
fbshipit-source-id: 68f1e10eb9d4b99552bb158f6ad7e6ff0f7cc1c4
