Syntax error configuring Nest thermostat on Hass.io 0.63.2

Configuration
1

I am getting the following syntax error trying to install the Nest component:

Testing configuration at /config
2018-02-17 11:59:48 ERROR (MainThread) [homeassistant.config] Invalid config for [homeassistant]: [nest] is an invalid option for [homeassistant]. Check: homeassistant->customize->nest. (See /config/configuration.yaml, line 2). 
Failed config
  homeassistant: 
    customize: [source /config/configuration.yaml:13]
      nest: [source /config/customize.yaml:4]
        client_id: [id deleted]
        client_secret: [secret deleted]
      sensor.yr_symbol: [source /config/customize.yaml:1]
        friendly_name: Weather

I’m a new user as of yesterday and feel I’m missing something simple as I find no similar problems searching the forums. The documentation seems to say that the Nest code should be in the configuration.yaml file but this isn’t working for me.

Pointers to the section of documentation I seem to be missing?

Thanks.