added eta to metrics.json (#390)
added eta to metrics.json (#390)

Summary:
Hi there ! This is in regard to https://github.com/facebookresearch/detectron2/issues/389 .

I linted and tested on my local computer and everything looks fine.
Pull Request resolved: https://github.com/facebookresearch/detectron2/pull/390

Differential Revision: D18707114

Pulled By: ppwwyyxx

fbshipit-source-id: e3f7c627654ca62c1a2db121428d952c1485a5ca

facebookresearch/detectron2,facebookresearch/detectron2,facebookresearch/detectron2