Add README link to testing docs.
Add README link to testing docs.

Futurelearn/vanity,HealthyDelivery/vanity,peterkovacs/vanity,assaf/vanity,HealthyDelivery/vanity,peterkovacs/vanity,Futurelearn/vanity,peterkovacs/vanity,Futurelearn/vanity,assaf/vanity,HealthyDelivery/vanity,assaf/vanity