Mailer README doesn't include .env instructions

[j-norwood-young]

The Mailer documentation is self-standing and complete except that it doesn't include the instructions for the .env file.

[rootpd]

Aren't the comments within .env.example explanatory enough? We didn't want to duplicate that information also to README, it would get inconsistent over time.

[rootpd]

Maybe we could add the information about .env.example into the README? Would that help you when you read it before?

(maybe somewhere right at the top of readme and everywhere .env is mentioned)

[j-norwood-young]

Yeah, that would help tremendously. Just when working through the installation instructions, I hit the problem. It wasn't difficult to solve, it just felt like the instructions were incomplete.