Trivial comment update in autograd/function.h (#15529)
Summary:
I removed the explanation on `num_inputs` parameter. This parameter was removed in #8168
colesbury
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15529
Differential Revision: D13547854
Pulled By: soumith
fbshipit-source-id: 8a9ac58f2c93a2533b82ec63089477166ed0bcb9
