drivers: can: calling can_stop() shall abort any pending transmissions

Update the documentation for can_stop() to mention that it shall abort any
pending CAN frame transmissions.

Fixes: #50545

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
diff --git a/include/zephyr/drivers/can.h b/include/zephyr/drivers/can.h
index 419b720..2b58a40 100644
--- a/include/zephyr/drivers/can.h
+++ b/include/zephyr/drivers/can.h
@@ -978,7 +978,8 @@
  * @brief Stop the CAN controller
  *
  * Bring the CAN controller into `CAN_STATE_STOPPED`. This will disallow the CAN controller from
- * participating in CAN communication and disable the CAN transceiver, if supported.
+ * participating in CAN communication, abort any pending CAN frame transmissions, and disable the
+ * CAN transceiver, if supported.
  *
  * @see can_start()
  * @see can_transceiver_disable()