updated "API Reference"

en/api-reference/button/button.rst

@@ -0,0 +1,70 @@
+Button API
+***********
+
+-----------------------------
+
+Function
+---------
+
+isPressed()
+
+isReleased()
+
+pressedFor(timeout)
+
+wasPressed(callback=None) 
+wasReleased(callback=None)
+releasedFor(timeout, callback=None)
+
+
+
+---------------------
+
+Usage
+------
+
+.. code:: python
+
+    from m5stack import *
+    from machine import SPI, Pin
+    from display import LCD
+    import utime
+
+    spi = SPI(1, baudrate=32000000, mosi=Pin(23), miso=Pin(19), sck=Pin(18))
+
+    lcd = LCD(spi = spi) #lcd init
+    
+    while True:
+      if buttonA.wasPressed():
+        lcd.print('Button A was Pressed\n')
+
+      if buttonA.wasReleased():
+        lcd.print('Button A was Released\n')
+
+      if buttonA.pressedFor(1.5):
+        lcd.print('Button A pressed for 1.5s\n')
+
+      if buttonA.releasedFor(2):
+        lcd.print('Button A released for 2s press hold\n')
+
+      utime.sleep(0.1)
+
+
+.. code:: python
+
+    #Button Callback
+
+    from m5stack import * 
+
+    def on_wasPressed():
+      lcd.print('Button B was Pressed\n')
+
+    def on_wasReleased():
+      lcd.print('Button B was Released\n')
+
+    def on_releasedFor():
+      lcd.print('Button B released for 1.2s press hold\n')
+
+    buttonB.wasPressed(on_wasPressed)
+    buttonB.wasReleased(on_wasReleased)
+    buttonB.releasedFor(1.2, on_releasedFor)