Update docs for the state_listener_manager API.

include/relay_chn.h

@@ -63,9 +63,12 @@ typedef enum relay_chn_state_enum relay_chn_state_t;
 
 /**
  * @brief Relay channel state change listener.
- * 
+ *
  * An optional interface to listen to the channel state change events.
- * 
+ * The listeners SHOULD be implemented as light functions and SHOULD NOT contain
+ * any blocking calls. Otherwise the relay_chn module would not function properly
+ * since it is designed as event driven.
+ *
  * @param chn_id The ID of the channel whose state has changed.
  * @param old_state The old state of the channel.
  * @param new_state The new state of the channel.

src/relay_chn.c

@@ -85,10 +85,12 @@ typedef struct relay_chn_type {
     esp_timer_handle_t inertia_timer;       ///< Timer to handle the opposite direction inertia time.
 } relay_chn_t;
 
-
+/**
+ * @brief Structure to manage the state change listeners. 
+ */
 struct relay_chn_state_listener_manager_type {
-    uint8_t listener_count;
-    relay_chn_state_listener_t *listeners;
+    uint8_t listener_count;                 ///< The number of registered listeners.
+    relay_chn_state_listener_t *listeners;  ///< The list that holds references to the registered listeners.
 } relay_chn_state_listener_manager;