Add flag for token collection (#4282)

* Add flag for token collection

Add flag for token collection as it is a required param.

* Update index.md

* add example

* Update src/connections/destinations/catalog/customer-io-actions/index.md

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Co-authored-by: Niall Brennan <[email protected]>
Co-authored-by: stayseesong <[email protected]>

Author: 3 people

src/connections/destinations/catalog/customer-io-actions/index.md

@@ -50,3 +50,6 @@ For example, if you send an event with a `purchase_time` trait of `2006-01-02T18
 
 Customer.io makes an exception for the `created_at` trait, converting ISO-8601 timestamps or any values supported by JavaScript `Date` objects to Unix timestamps.
 
+## Device token collection
+
+Segment does not automatically collect push notification tokens. These parameters are required by Customer.io, requiring logic to be implemented to collect these values. As an example, you can use [this plugin](https://github.com/segmentio/analytics-react-native/tree/master/packages/plugins/plugin-device-token){:target="_blank"} to collect the Firebase Cloud Messaging device token for React Native.