Update documentation to account for the changes in #24952.
docs/swarm/swarm-tutorial/rolling-update.md doesn't need any changes,
but the CLI reference pages should show the current help text.
drain-node.md no longer needs to specify --update-parallelism 1 in its
example.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Upstream-commit: 933ba8d7f7f95ad0bac97c39ffb3cdf1a5634cc6
Component: engine
0744d6df7d