Documentation: Add wd_restart_next() API description

Add documentation for the newly introduced wd_restart_next() API,
    describing its purpose and usage.

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

Documentation/reference/os/time_clock.rst

@@ -491,6 +491,7 @@ with NuttX tasks.
 
 - :c:func:`wd_start`
 - :c:func:`wd_restart`
+- :c:func:`wd_restart_next`
 - :c:func:`wd_cancel`
 - :c:func:`wd_gettime`
 - Watchdog Timer Callback
@@ -555,6 +556,25 @@ with NuttX tasks.
   :return: Zero (``OK``) is returned on success; a negated ``errno`` value
     is return to indicate the nature of any failure.
 
+.. c:function:: int wd_restart_next(FAR struct wdog_s *wdog, clock_t delay)
+
+  This function restarts the specified watchdog timer using a new delay
+  value, but schedules the next expiration based on the previous
+  expiration time (wdog->expired + delay).  This allows the watchdog to
+  maintain a consistent periodic interval even if there is some delay in
+  handling the expiration callback.
+
+  It can be used when the user wants to restart a watchdog for a different
+  purpose or continue periodic timing based on the previous timeout point.
+
+  :param wdog: Pointer to the watchdog timer to restart
+  :param delay: Delay count in clock ticks
+
+  **NOTE**: The parameter must be of type ``wdparm_t``.
+
+  :return: Zero (``OK``) is returned on success; a negated ``errno`` value
+    is return to indicate the nature of any failure.
+
 .. c:function:: int wd_cancel(FAR struct wdog_s *wdog)
 
   This function cancels a currently running