README: no more nightly builds; use apt rather than dpkg

You have four installation options:

* Nightly `.deb` builds for Debian-based distributions

* `.deb` releases for Debian-based distributions

* Installing the latest release from CPAN

* Installation from source

* Using a Docker image

You can run `hafas-m --version` to verify this. Documentation is available via

`man hafas-m`.

### Nightly Builds for Debian

### Release Builds for Debian

[lib.finalrewind.org/deb](https://lib.finalrewind.org/deb) provides Debian

packages of both development and release versions. Note that these are not part

of the official Debian repository and are not covered by its quality assurance

process.

packages of all release versions. Note that these are not part of the official

Debian repository and are not covered by its quality assurance process.

To install the latest release, run:

```

wget https://lib.finalrewind.org/deb/libtravel-status-de-deutschebahn-perl_latest_all.deb

sudo dpkg -i libtravel-status-de-deutschebahn-perl_latest_all.deb

sudo apt --fix-broken install

sudo apt install ./libtravel-status-de-deutschebahn-perl_latest_all.deb

rm libtravel-status-de-deutschebahn-perl_latest_all.deb

```

For a (possibly broken) development snapshot of the Git master branch, run:

```

wget https://lib.finalrewind.org/deb/libtravel-status-de-deutschebahn-perl_dev_all.deb

sudo dpkg -i libtravel-status-de-deutschebahn-perl_dev_all.deb

sudo apt --fix-broken install

rm libtravel-status-de-deutschebahn-perl_dev_all.deb

```

Note that dpkg, unlike apt, does not automatically install missing

dependencies. If a dependency is not satisfied yet, `dpkg -i` will complain

about unmet dependencies and bail out. `apt --fix-broken install` installs

these dependencies and also silently finishes the

Travel::Status::DE::DeutscheBahn installation.

Uninstallation works as usual:

```