The main site has released a branch of SO that provides documentation...
I read the walk-through and it seemed a touch baroque for us, but nonetheless am wondering if this is in the pipeline.
Not for a while: see Allow Documentation in other Stack Exchange communities on the main meta.
We'd love to roll this out network-wide, but we've been in public beta for less than a week [about a month now], and the product isn't quite ready to go elsewhere. We are actively iterating on docs by fixing bugs and making improvements. Once it is known to work, then we can discuss the possibility of adding it to other sites but that won't be for 6-8 weeks [a running meta joke meaning "We have no idea when, don't wait].
I asked them if they could allow early access for a few clearcut examples from technical sites that would definitely fit. e.g. sites around some software platform where there's an API people code against, where it'd work almost identically to how it does for StackOverflow. I can't think of any such clear cut examples for Travel. Their answer was:
In principle it's a good idea, but I guess it will take awhile. The [documentation] rep system is quite broken and may be very complicated to fix and the quality of the content is also not very high and there are still glitches in the user interface. But if all these problems are solved, why not.
So it'll be open to other sites one day, but not for a long while, not until well after they've got the formula right, and Travel will be quite far down the list behind technical / coding related sites where it's obvious how they fit.
I can't really think of any tags here where we'd want to build "documentation" libraries.