doc: clarify the meaning of overflow in pcnt driver

Closes https://github.com/espressif/esp-idf/issues/10039

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

@@ -227,7 +227,7 @@ You can check current count value at any time by calling :cpp:func:`pcnt_unit_ge
 
 .. note::
 
-    The returned count value is a **signed** integer, where the sign can be used to reflect the direction. The internal counter will overflow when it reaches high or low limit, but this function doesn't compensate for that loss.
+    The returned count value is a **signed** integer, where the sign can be used to reflect the direction. The internal counter will be cleared to zero automatically when it reaches high or low limit, but this function doesn't compensate for that loss.
 
 .. code:: c
 

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

@@ -227,7 +227,7 @@ PCNT 单元的滤波器可滤除信号中的短时毛刺，:cpp:type:`pcnt_glitc
 
 .. note::
 
-    返回的计数器数值是一个 **带符号** 的整数，符号代表计数方向。计数器的数值大于等于最大值或小于等于最小值时，计数器会溢出。
+    返回的计数器数值是一个 **带符号** 的整数，符号代表计数方向。计数器的数值大于等于最大值或小于等于最小值时，计数器会自动清零。
 
  .. code:: c