docs(stop): exit 1 also covers a row that could not be read (Issue #71)

Refs #71

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/multi-agent-mux-stop/scripts/stop_session.sh

@@ -29,7 +29,7 @@
 #
 # Exit codes:
 #   0 = success (or already-stopped no-op; or a session with no row closed)
-#   1 = YAML not found / not registered and not on the herdr server
+#   1 = YAML not found / its row unreadable / not registered and not on the herdr server
 #   2 = invalid args | 3 = interactive confirmation required (--yes 누락)
 #   4 = purge aborted (herdr session or an agent process holding the conversation survived the kill chain)
 #   5 = no row, and herdr runs the session outside this workspace (refused, nothing changed)