pub.dev example page link needs to be updated

[JustinHorn]

On https://pub.dev/packages/flutter_hooks/example the example link has not been updated when the repo moved to the multiple package structure. On click of the link one now lands on a 404.

Pls update the link to redirect to https://github.com/rrousselGit/flutter_hooks/blob/master/packages/flutter_hooks/example/lib/main.dart