outdated docs default tls version

heyjo :3

i think the docs are outdated on the minimum tls version.
honestly i am not comfy reading go and don't know enough about mail.
i was email rfc's and in 8997 it says that the minimum TLS version used by an MSP should be 1.2 or greater.
in the [docs](https://maddy.email/reference/tls/) it says that maddy uses tls 1.0 as its minimum version.
when running maddy without any tls options with curl and setting the tls protocol via `--tls-max` i get anything below 1.2 rejected.
i think the way i got the code is that in the default case the `tls.Config.MinVersion` and `tls.Config.MaxVersion` are set to O. honestly i didn't bother to spend more time reading the go lib for crypto much beyond their comment that the default tls version is 1.2 and found [this PR from a year back](https://github.com/golang/go/issues/62459) saying that they bumped it.
the docs weren't updated since then (`tls.md` at least).
that's why i guess everything is fine, it's just that the docs are outdated.

best regards

Commencez par tls.md et comparez la version minimale de TLS qui y est indiquée avec le comportement décrit à l’aide de curl et de --tls-max, puis consultez la discussion liée sur les valeurs par défaut de TLS de Go pour avoir le contexte. Le travail est terminé lorsque la documentation décrit correctement la version minimale de TLS par défaut de maddy et ne prétend plus qu’il s’agit de TLS 1.0 si la valeur par défaut rejette les versions antérieures.

Rédigé par le modèle d'indexation à partir du texte de l'issue.