There is this guy, Eric Holscher, who has been doing FOSS development for quite a while. He's been on GitHub since 2008, and got involved in Gittip not long after it started in 2012. Not long after that, Eric started thinking about how open source software developers have all kinds of conferences and have many communities they can join and learn from each other, while those who write documentation, especially for FOSS, typically work all alone in a vacuum.
So why not have a conference for documentation writers (and developers who want to hook up with writers who can help them make high-quality docs)? Don't limit it to FOSS, but make sure that's the emphasis. Call the conference 'Write the Docs' and have the first conference in Portland, Oregon, in 2013. Which is exactly what Eric did. A year later, a second 'Write the Docs' conference is scheduled in Budapest (Hungary) at the end of March, and the next Portland conference is set for May 5.