Merge #1035

1035: [doc] port 443 instead of 440 r=mergify[bot] a=hoellen

## What type of PR?

fix documentation

## What does this PR do?

### Related issue(s)
#1018 

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


Co-authored-by: hoellen <dev@hoellen.eu>

docs/reverse.rst

@@ -137,7 +137,7 @@ which will dump the certificates as ``PEM`` files, readable for Nginx. The ``fro
 
 To set this up, first set ``TLS_FLAVOR=mail`` in your ``.env``. This tells ``mailu/front`` not to try to request certificates using ``letsencrypt``,
 but to read provided certificates, and use them only for mail-protocols, not for ``HTTP``.
-Next, in your ``docker-compose.yml``, comment out the ``port`` lines of the ``front`` section for port ``…:80`` and ``…:440``.
+Next, in your ``docker-compose.yml``, comment out the ``port`` lines of the ``front`` section for port ``…:80`` and ``…:443``.
 Add the respective Traefik labels for your domain/configuration, like
 
 .. code-block:: yaml