[Event Grid] created async samples + updated samples/README.md#16171

Closed

swathipil wants to merge 4 commits intoAzure:masterfrom swathipil:swathipil/eg/async-samples

+518-21

Commits on Jan 12, 2021

moved existing eg samples to sync_samples folder
swathipil
committed

Commits on Jan 14, 2021