docs: add edit_schedule manager MCP tool to turn-loop.md (follow-up to #478)

docs/turn-loop.md

@@ -342,6 +342,14 @@ meta's.
   one-shot otherwise. Even self-targeted schedules go through
   approval (use `remind` for unapproved self-wake). Long downtime
   fires once per recurring row on resume (catch-up clamp).
+- `edit_schedule(id, body?, description?, interval_seconds?, next_fire_at_unix?, targets_add?, targets_remove?)` —
+  partial-update a schedule (#474/#478). Pass only the fields to
+  change; absent fields are left alone. `targets_add` / `targets_remove`
+  mutate the recipient list in the same transaction; re-adding a
+  previously-cancelled target drops its tombstone + history (fresh
+  start). Clearing a scalar (e.g. `interval_seconds: null`) flips
+  recurring→one-shot. Refuses cancelled rows. Same authorization as
+  `cancel_schedule`.
 - `cancel_schedule(id, targets?)` — cancel a schedule. Omit
   `targets` / pass empty to cancel the whole schedule; pass a list
   to cancel just those recipients (auto-cancels when every target