Add one line comment between SSL files in .env for Docker Compose clarifying path

[wgalanciak]

Description

The new .env.template makes it much clearer what to do with the FQDN and SSL keys however I find it a bit confusing that the SSL file needs to be in a subdirectory but the .env file makes it look like it should/could just be next to that file itself.

We should add a simple comment like:

# SSL files should be placed in nginx/ssl

[waldekCT]

Fixed ✅