Clarify semantic conventions around span start and end time#592

Merged

bogdandrutu merged 6 commits intoopen-telemetry:masterfrom toumorokoshi:feature/span-duration-conventions

Jun 30, 2020

+20-1

Commits on May 9, 2020

Adding http semantic conventions for span start and end times.
toumorokoshi
committed

Commits on May 10, 2020

Commits on May 16, 2020

Addressing feedback
toumorokoshi
committed

Commits on May 19, 2020