Paid Stats: update copy

[crisbusquets]

With Paid Stats, some sections are behind the paywall/upgrade button. There are some differences between the current implementation and the design in Figma:

Proposal

Copy changes

• Referrers section: Learn where your visitors come from and optimize your content strategy
• Clicks: Learn what your visitors are clicking to discover popular topics and formats
• Authors: _Finding your top authors reveals your audience's favorite writing styles and perspectives

We could also update the CTA, as we tend to use Upgrade in Calypso.

[allilevine]

Copy changes

We changed these from the Figma in response to editorial feedback: #85940 (comment)

We could also update the CTA, as we tend to use Upgrade in Calypso.

Should we go ahead and change "Unlock" to "Upgrade plan," or should we see how "Unlock" performs first?

[crisbusquets]

Should we go ahead and change "Unlock" to "Upgrade plan," or should we see how "Unlock" performs first?

Great question @allilevine. I normally lean towards consistency, but I can see why in this case it might be better to use "Unlock". Let's keep it like this and decide the next steps once we have data.