more information on "has_social_referral" for traffic-source data

[claireboyd]

What kind of issue?

• Feature Request?
• Bug
• [ X] More Information

User story

Please provide us with a description of the issue as a user story
As a student researcher, I would like to learn more about what the "has_social_referral" variable means for the traffic source data, so that I can better report the results for a school project

Acceptance Criteria

• How is has_social_referral captured?
• What counts as a social referral?

Notes

Tasks (Optional)