doc(client_get_some_icon) Improve description

objects/client.c

@@ -4313,11 +4313,25 @@ luaA_client_get_icon_sizes(lua_State *L, client_t *c)
 }
 
 /** Get the client's n-th icon.
+ *
+ * The icon index can be deternined by inspecting the `icon_sizes` property first.
+ *
+ * The user has the responsibility to test the value returned by this function
+ * to ensure an icon have been returned.
+ *
+ * It is recommended to use the `awful.widget.clienticon` widget when the
+ * client icon is used in a widget structure.
+ *
+ * Note that this function tests the provided index and raise an "invalid icon
+ * index" error if the provided index doesn't exist in the client's icons list
+ * (by raising this error, the function will return `nil` to the caller).
  *
  * @tparam interger index The index in the list of icons to get.
  * @treturn surface A lightuserdata for a cairo surface. This reference must be
  * destroyed!
  * @method get_icon
+ * @see icon_sizes
+ * @see awful.widget.clienticon
  */
 static int
 luaA_client_get_some_icon(lua_State *L)