docs: restructure documentation

This rewrite follows the principles of https://diataxis.fr/

Co-authored-by: Erik Michelson <github@erik.michelson.eu>
Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Erik Michelson <github@erik.michelson.eu>

docs/content/tutorials/setup.md

@@ -0,0 +1,82 @@
+# Setup
+
+After completing this tutorial you'll have your own HedgeDoc instance running.
+We will use [Docker][docker-docs] to accomplish this.
+
+<!-- markdownlint-disable proper-names -->
+
+1. Open the terminal of the machine you want to install HedgeDoc on.
+
+2. Check if you have Docker installed by running `docker --version`. 
+   The response should contain some version number greater than `20.10.13`.
+    - If not please refer to [the Docker install guide][docker-install] to install Docker.
+
+3. Create a new directory for your HedgeDoc instance: `mkdir -p /opt/hedgedoc`.
+
+4. Change into the directory with `cd /opt/hedgedoc`.
+
+5. Download these files:
+   - `curl -o .env https://docs.hedgedoc.dev/files/setup-docker/config.env`
+   - `curl -o Caddyfile https://docs.hedgedoc.dev/files/setup-docker/Caddyfile`
+   - `curl -o docker-compose.yml https://docs.hedgedoc.dev/files/setup-docker/docker-compose.yml`
+
+6. Open the file `.env` in the editor of your choice (for example with `nano`) and edit the
+   following variables:
+   - `HD_BASE_URL`: This should contain the full url you intend to run HedgeDoc on (e.g. for the
+     demo this would be `https://demo.hedgedoc.org`). If you just want to run HedgeDoc on your
+     local machine for now `https://hedgedoc.localhost` should be sufficient for testing.
+   - `HD_SESSION_SECRET`: This should contain a long and random secret for your login sessions.
+     You can generate it with `pwgen -s 64` or any other way you see fit.
+   - `HD_DATABASE_PASS`: This should contain a strong password than `password` for your database.
+     You can again use `pwgen -s 64` to generate it.
+
+7. Start the Docker containers by running `docker compose up -d`.
+
+8. Navigate your browser to the url you chose in step 6. Your instance is now ready to use.
+
+<!-- markdownlint-enable proper-names -->
+
+You can now play around with your HedgeDoc instance and read about next steps
+as either [a new user](#for-users) or [an admin](#for-admins).
+
+## Next Steps
+
+### For Users
+
+- [Creating a user account][tutorials/user]
+- [Creating your first note][tutorials/first-note]
+- [Creating your first presentation][tutorials/first-presentation]
+
+### For admins
+
+- [How to use a reverse proxy][reverse-proxying]
+- [How to back up HedgeDoc][backups]
+- [How to use other authentication methods][auth-methods]
+- [Advanced configuration options][config]
+
+## Troubleshooting
+
+### Port already used
+
+```text
+Error response from daemon: driver failed programming external connectivity: Bind for 0.0.0.0:80
+failed: port is already allocated.
+```
+
+If you see this error, it means there is already something running on your machine that uses
+port `80` or `443`. The easiest fix for this is to stop the other application.
+If you want to run multiple applications on that port on your server you may want to read our guide
+about [reverse proxying][reverse-proxying].
+
+[docker-docs]: https://docs.docker.com/
+[docker-install]: https://docs.docker.com/engine/install/
+
+[tutorials/user]: /tutorials/user/
+[tutorials/first-note]: /tutorials/first-note/
+[tutorials/first-presentation]: /tutorials/first-presentation/
+
+[reverse-proxying]: /how-to/reverse-proxy/
+[backups]: /how-to/backup/
+[auth-methods]: /how-to/auth/
+
+[config]: /references/config/