Certificates for HTTPS

This is the diff between the backup and the current copy.

# Certificates for HTTPS

We use `certbot` to generate the certificates.
To regenerate them if something broke:

```
sudo certbot --expand -d grenzland.club -d wiki.grenzland.club
```

Running certbot requires a site on port 80.

Show the log:

```
sudo journalctl -u certbot.service
```

The error in question:

> Failed to renew certificate grenzland.club with error: Unable to find a virtual host listening on port 80 which is currently needed for Certbot to prove to the CA that you control your domain. Please add a virtual host for port 80.

This site is provided by `/etc/apache2/sites-enabled/000-default.conf`.
All it does is redirect `http://grenzland.club` to `https://grenzland.club`.

If scripts need to run after `certbot`, put them in the appropriate subdirectory of `/etc/letsencrypt/renewal-hooks/`.
Typically that is `/etc/letsencrypt/renewal-hooks/deploy/prosody.sh` since it uses the same certificates as the web server.

Also `/etc/letsencrypt/renewal-hooks/deploy/ngircd.sh` because `ngircd` needs to reload its config and certs (which it does when it receives SIGHUP).

== ngircd

If the IRC server doesn't know about the new certs, reload its config:

```
sudo kill -HUP `sudo cat /var/run/ngircd/ngircd.pid`
```