docs(deploy): note the one-time client restart in the unit itself

The migration step was in the PR discussion and in the operator runbook, but
not in the file that actually ships to consumers. A client whose container
started while the daemon ran without RuntimeDirectoryPreserve is still pinned
to the old inode and needs one restart; every restart after that is
transparent.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Lutherwaves

deploy/openbloxd.service

@@ -23,6 +23,11 @@ RuntimeDirectoryMode=0750
 # pinned to the old inode, which is now orphaned and empty, so every call
 # fails with ENOENT until that client is restarted too. Restarting the broker
 # must not require restarting its callers.
+#
+# One-time migration: a client whose container started while the daemon was
+# running WITHOUT this setting is still pinned to the old inode, so it needs a
+# single restart after this unit is installed. Restarts are transparent from
+# then on.
 RuntimeDirectoryPreserve=yes
 Restart=on-failure