Add note on API keys

README.md

@@ -25,8 +25,9 @@ pip install -e silo
 ```python
 import silo
 
-variables = ['daily_rain', 'max_temp', 'min_temp']
+# Reigster for API key at https://silo.longpaddock.qld.gov.au/register
 api_key = 'BcfJnotlnVgX9gyLmZh2dURqNH8xAD3m8Am7V9OY'
+variables = ['daily_rain', 'max_temp', 'min_temp']
 start = '18990101'
 finish = '20180101'
 lat = -33