chore: added instructions for using https://ethereal.mail in development

README.md

@@ -15,7 +15,9 @@ The webpage should now appear on `localhost:8080` and the django REST api browse
 
 ## Mail Setup
 ### Mail setup in development environment
-https://ethereal.email can create fake credentials, and the service can show all emails that were attempted sent (without actually sending them). This is also mentioned in `postfix/.env.default`.
+https://ethereal.email can create fake credentials, and the service can show all emails that were attempted sent (without actually sending them). This is also mentioned in `postfix/.env.default`. To use the service:
+- Copy `postfix/.env.default` to `postfix/.env`
+- Replace values with credentials from our https://ethereal.email
 
 ### Mail setup in production environment
 If you want to be able to actually send emails: