Update responders.md (#1369)

deiuch · alexreardon · commit 286b2a5241a9 · 2019-06-20T14:12:22.000+10:00
Missing `mode` in the type description of DragStart.
diff --git a/docs/guides/responders.md b/docs/guides/responders.md
@@ -76,6 +76,7 @@ type DragStart = {|
   draggableId: DraggableId,
   type: TypeId,
   source: DraggableLocation,
+  mode: MovementMode,
 |};
 
 type DraggableLocation = {|
