docs(mcpwm): add missing explanation about keep_io_conf_at_exit

Closes https://github.com/espressif/esp-idf/issues/12579

components/esp_driver_mcpwm/include/driver/mcpwm_cap.h

@@ -136,7 +136,9 @@ typedef struct {
     int intr_priority;               /*!< MCPWM capture interrupt priority,
                                           if set to 0, the driver will try to allocate an interrupt with a relative low priority (1,2,3) */
     uint32_t prescale;               /*!< Prescale of input signal, effective frequency = cap_input_clk/prescale */
-    struct {
+
+    /// Extra configuration flags for capture channel
+    struct extra_flags {
         uint32_t pos_edge: 1;          /*!< Whether to capture on positive edge */
         uint32_t neg_edge: 1;          /*!< Whether to capture on negative edge */
         uint32_t pull_up: 1;           /*!< Whether to pull up internally */

docs/en/api-reference/peripherals/mcpwm.rst

@@ -204,10 +204,11 @@ Next, to allocate a capture channel, you can call the :cpp:func:`mcpwm_new_captu
 - :cpp:member:`mcpwm_capture_channel_config_t::intr_priority` sets the priority of the interrupt. If it is set to ``0``, the driver will allocate an interrupt with a default priority. Otherwise, the driver will use the given priority.
 - :cpp:member:`mcpwm_capture_channel_config_t::gpio_num` sets the GPIO number used by the capture channel.
 - :cpp:member:`mcpwm_capture_channel_config_t::prescale` sets the prescaler of the input signal.
-- :cpp:member:`mcpwm_capture_channel_config_t::pos_edge` and :cpp:member:`mcpwm_capture_channel_config_t::neg_edge` set whether to capture on the positive and/or falling edge of the input signal.
-- :cpp:member:`mcpwm_capture_channel_config_t::pull_up` and :cpp:member:`mcpwm_capture_channel_config_t::pull_down` set whether to pull up and/or pull down the GPIO internally.
-- :cpp:member:`mcpwm_capture_channel_config_t::invert_cap_signal` sets whether to invert the capture signal.
-- :cpp:member:`mcpwm_capture_channel_config_t::io_loop_back` sets whether to enable the Loop-back mode. It is for debugging purposes only. It enables both the GPIO's input and output ability through the GPIO matrix peripheral.
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pos_edge` and :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::neg_edge` set whether to capture on the positive and/or falling edge of the input signal.
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pull_up` and :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pull_down` set whether to pull up and/or pull down the GPIO internally.
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::invert_cap_signal` sets whether to invert the capture signal.
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::io_loop_back` sets whether to enable the Loop-back mode. It is for debugging purposes only. It enables both the GPIO's input and output ability through the GPIO matrix peripheral.
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::keep_io_conf_at_exit` sets whether to keep the GPIO configuration when the capture channel is deleted.
 
 The :cpp:func:`mcpwm_new_capture_channel` will return a pointer to the allocated capture channel object if the allocation succeeds. Otherwise, it will return an error code. Specifically, when there is no free capture channel left in the capture timer, this function will return the :c:macro:`ESP_ERR_NOT_FOUND` error.
 

docs/zh_CN/api-reference/peripherals/mcpwm.rst

@@ -204,10 +204,11 @@ MCPWM 组有一个专用定时器，用于捕获特定事件发生时的时间
 - :cpp:member:`mcpwm_capture_channel_config_t::intr_priority` 设置中断的优先级。如果设置为 ``0``，则会分配一个默认优先级的中断，否则会使用指定的优先级。
 - :cpp:member:`mcpwm_capture_channel_config_t::gpio_num` 设置捕获通道使用的 GPIO 编号。
 - :cpp:member:`mcpwm_capture_channel_config_t::prescale` 设置输入信号的预分频器。
-- :cpp:member:`mcpwm_capture_channel_config_t::pos_edge` 和 :cpp:member:`mcpwm_capture_channel_config_t::neg_edge` 设置是否在输入信号的上升沿和/或下降沿捕获时间戳。
-- :cpp:member:`mcpwm_capture_channel_config_t::pull_up` 和 :cpp:member:`mcpwm_capture_channel_config_t::pull_down` 设置是否在内部拉高和/或拉低 GPIO。
-- :cpp:member:`mcpwm_capture_channel_config_t::invert_cap_signal` 设置是否取反捕获信号。
-- :cpp:member:`mcpwm_capture_channel_config_t::io_loop_back` 设置是否启用回环模式。该模式仅用于调试，使用 GPIO 交换矩阵外设同时启用 GPIO 输入和输出。
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pos_edge` 和 :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::neg_edge` 设置是否在输入信号的上升沿和/或下降沿捕获时间戳。
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pull_up` 和 :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::pull_down` 设置是否在内部拉高和/或拉低 GPIO。
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::invert_cap_signal` 设置是否取反捕获信号。
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::io_loop_back` 设置是否启用回环模式。该模式仅用于调试，使用 GPIO 交换矩阵外设同时启用 GPIO 输入和输出。
+- :cpp:member:`mcpwm_capture_channel_config_t::extra_flags::keep_io_conf_at_exit` 设置是否在删除通道时保留 GPIO 的相关配置。
 
 分配成功后，:cpp:func:`mcpwm_new_capture_channel` 将返回一个指向已分配捕获通道的指针。否则，函数将返回错误代码。具体来说，当捕获定时器中没有空闲捕获通道时，将返回 :c:macro:`ESP_ERR_NOT_FOUND` 错误。