Getting Started: updated note in "Training and Evaluation in Command Line"
Getting Started: updated note in "Training and Evaluation in Command Line"

Summary: Pull Request resolved: https://github.com/facebookresearch/detectron2/pull/1827

Reviewed By: alexander-kirillov

Differential Revision: D23011996

Pulled By: ppwwyyxx

fbshipit-source-id: 11dda4754bbcd0fa8ee51f947d8f51aa583d9202

facebookresearch/detectron2,facebookresearch/detectron2,facebookresearch/detectron2