Adding a docstring for memoryless in observer args (#67690)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67690
see title [skip ci]
Test Plan:
python setup.py develop
Imported from OSS
Reviewed By: ejguan
Differential Revision: D32107512
fbshipit-source-id: da5668339716d44720672f7b71a991b23530461e
