Fix hetzner typo
* [AWS](quickstart-aws.md)
* [DigitalOcean](quickstart-digitalocean.md)
* [Google Compute Engine (GCE)](quickstart-gce.md)
- * [Hetnzer](quickstart-hetzner.md)
+ * [Hetzner](quickstart-hetzner.md)
* [Packet](quickstart-packet.md)
* [OpenStack](quickstart-openstack.md)
* [Frequently Asked Questions](frequently_asked_questions.md)
