Update service.md

[nlko]

I was following the doc and ran into a few things. I managed to make it work this way. I use express instead of hapi but I don't think that matters in that case.

[tjwebb]

@nlko thanks for the feedback! The docs may seem a little off because they were written for the upcoming release of trails v3, which will be finished in the next couple of weeks. I'll look through your changes, thanks.