Thanks for the link edits, such boards always screw them up
Regarding your 'check_dig' question - thanks for the pointer. I missed something on the release 2 weeks ago - 'latest' should only reflect the latest released docs version, but not the 'next' branch. dig was added to next. It's changed now.
Will be in one of the next versions, meanwhile feel free to use your own check command definition, or use sort of "snapshot" builds from ports, if that exists (I'm not a FreeBSD user, just doing icinga support wherever possible).
In terms of more telling examples - that's true, but still one of those "how to make it right" things. We intentionally wrote every documentation piece in markdown, so it's easy to edit, and we happily receive patches/pull requests with your findings and input. Meanwhile you should not use any web resources, but only docs.icinga.org or the plain markdown files as main reference. Plenty of things changed towards the final 2.0.0 release, but since we are an open project, testers and users have been publishing their old guides which are merely outdated these days.
There's an issue open already:
https://dev.icinga.org/issues/5474
When it comes to the documentation, it's presented by the Icinga Web 2 docs module, which is still undergoing heavy development. A search bar, and other stuff will be added once there is time again.
The wiki shouldn't be used as reference, you will either use
https://dev.icinga.org for bugs, or
http://docs.icinga.org for online documentation. More information is listed at
https://www.icinga.org/community/