Document the length parameter of find()

Reference:
https://github.com/arduino/ArduinoCore-API/blob/1.0.0/api/Stream.h#L74-L75

Author: per1234

Language/Functions/Communication/Serial/find.adoc

@@ -14,20 +14,23 @@ title: Serial.find()
 
 [float]
 === 설명
-Serial.find() reads data from the serial buffer until the target string of given length is found. The function returns true if target string is found, false if it times out.
+Serial.find() reads data from the serial buffer until the target is found. The function returns true if target is found, false if it times out.
 
 Serial.find() inherits from the link:../../stream[stream] utility class.
 [%hardbreaks]
 
 
 [float]
 === 문법
-`Serial.find(target)`
+`Serial.find(target)` +
+`Serial.find(target, length)`
 
 [float]
 === 매개변수
 `target` : the string to search for (char)
 
+`length` : length of the target (size_t)
+
 [float]
 === 반환
 `bool`

Language/Functions/Communication/Stream/streamFind.adoc

@@ -22,7 +22,8 @@ This function is part of the Stream class, and can be called by any class that i
 
 [float]
 === 문법
-`stream.find(target)`
+`stream.find(target)` +
+`stream.find(target, length)`
 
 
 [float]
@@ -31,6 +32,8 @@ This function is part of the Stream class, and can be called by any class that i
 
 `target` : the string to search for (char)
 
+`length` : length of the target (size_t)
+
 [float]
 === 반환
 `bool`