Feature adoption template

This week we added a new feature adoption insight to our existing feature usage template. This insight will allow you to track how many users are adopting a particular feature. We've also renamed the feature usage template to "feature adoption".

Other improvements:

• We've redesigned our notification tab. Now the preview matches the Slack design. We've also added branding to the side panel.
• We've fixed a bug with how we display when there is no data in our feature retention and user retention templates.
• We now show articles for our templates.