Add issue template
Add issue template

Summary: Add issue template to pre-fill new issues on github with

Reviewed By: passy

Differential Revision: D4859854

fbshipit-source-id: 6c6e0ac217801d4915f186b866ed520a77d2faf0

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho