As part of an ongoing effort to centralize the ROS 2 documentation, we are going to retire the site https://docs.ros2.org . The content that is hosted there will be (some already has been) moved to https://docs.ros.org .
Early next week we’ll switch the DNS entry that points to docs.ros2.org to point to another host. Redirects have been setup so that any bookmarks or links to https://docs.ros2.org should continue to work. There will be a bit of downtime on docs.ros2.org when we do the switch, but it should be less than 24 hours.
I’ll update this thread once the DNS switch happens. If you notice any problems accessing https://docs.ros2.org (or https://docs.ros.org) after the switch, please reply to this thread and we will look into it.