The documentation for Swarm has been merged into the general documentation repo.
If you'd like to edit the current published version of the Swarm docs, do it in the master branch here: https://github.com/docker/docker.github.io/tree/master/swarm
If you need to document the functionality of an upcoming Swarm release,
use the vnext-swarm branch:
https://github.com/docker/docker.github.io/tree/vnext-swarm/swarm
As always, the docs in the general repo remain open-source and we appreciate your feedback and pull requests!