Added a hint to ethereal.email

ref #123

README.md

@@ -57,7 +57,7 @@ yarn docs
 
 ## ENV Vars
 > You can provide them via .env file or docker env vars.
-> You can use the `test:ci:generate_env` package script to generate a example env.
+> You can use the `test:ci:generate_env` package script to generate a example env (uses [ethereal.email](https://ethereal.email) as the mailserver).
 
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