A couple on months ago we started putting together an FAQ on RPKI  which led to quite a number of community contributions. We decided to expand upon this project and write comprehensive RPKI documentation, as an open source project.
Other than reading every RFC on the topic, this should give operators a good understanding of the moving parts involved, and how to use RPKI in the real world.
We got to the point where we think we have all the basics covered and made it available here:
As this is a project on GitHub  and managed using the Sphinx documentation tooling, we welcome corrections, additions, readability improvements and even translations.
Feel free to create an issue or pull request on GitHub.
Hope this is useful! See y’all in S.F.
Martin, Tim & Alex
The NLnet Labs RPKI Team