fix invalid param name

Author: tedder

README.rst

@@ -70,7 +70,7 @@ Usage Example
     wifi.radio.connect(wifi_ssid, wifi_password)
 
     pool = adafruit_connection_manager.get_radio_socketpool(wifi.radio)
-    ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_offset=3600)
+    ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_seconds=3600)
 
     while True:
         print(ntp.datetime)

examples/ntp_simpletest.py

@@ -20,7 +20,7 @@
 wifi.radio.connect(secrets["ssid"], secrets["password"])
 
 pool = socketpool.SocketPool(wifi.radio)
-ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_offset=3600)
+ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_seconds=3600)
 
 while True:
     print(ntp.datetime)