I don't buy the premise that the module needs a configuration in the first place.

Quite a bold statement considering you've no idea what module the OP is writing. Besides, he may have a different opinion about that.

And it hinders security to put a password in a world readable file.

The OP mentioned a username and a software revision. He didn't talk about passwords. Besides, he wasn't asking about opinions on whether it's a good idea to ask for usernames. He just wanted to know how to ask the user a question during installation time. How would you have answered his question if instead of This will be part of the module installation. he had written This will be part of the module testing phase.?