update Plugin Event migration docs to always return launchOptio… (#2719)
update Plugin Event migration docs to always return launchOptio… (#2719)

* update docs to always return launchOptions

We had an engineer at Airbnb follow the migration guide and remove the return statement thinking it wasn't needed. Turns out that it's a crucial piece and it would be good to keep things consistent and include it everywhere.

* remove trailing spaces
cypress-io/cypress-documentation,cypress-io/cypress-documentation