[Model Averaging] Update the documentation of PeriodicModelAverager (#70974)
Summary:
Here 20 is a bad example, since the warmup step is set as 100. 200 iterations will make much more sense.
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70974
Reviewed By: dagitses
Differential Revision: D33474576
Pulled By: rohan-varma
fbshipit-source-id: 4c7043108897848bde9503d77999971ad5567aa6
