Add additional language about data usage

## Feature Description

An increasing number of one-star reviews of the plugin mention it being used to collect data about users in seemingly nefarious ways:

* https://wordpress.org/support/topic/useless-420/
* https://wordpress.org/support/topic/i-trusted-google-blindly-you-be-careful/

We do have the checkbox and related language at setup for opt-in anonymous data, but it would be great to add some language somewhere that clarifies what the Google connection is used for, what is stored and how, and indicates that no additional data is being collected outside of what is required to power the service connections.

cc @abdullah1908

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## Acceptance criteria

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## Implementation Brief

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