fix typo errors in quantization-support.rst Line320 (#44447)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/44379
change
"`torch.per_channel_symmetric` — per tensor, symmetric"
to
"`torch.per_channel_symmetric` — per channel, symmetric"
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44447
Reviewed By: mruberry
Differential Revision: D29909645
Pulled By: ezyang
fbshipit-source-id: e1505d070ec2b335dd6503b528e6a2f3bda2f1e3
