docs: add getting started guide

Signed-off-by: David Mehren <git@herrmehren.de>

docs/content/setup/getting_started.md

@@ -0,0 +1,35 @@
+HedgeDoc 2 currently supports deployment using [Docker Compose](https://docs.docker.com/compose/install/).
+
+The `docker` folder in the root of our repo contains all files required to get started, deploying
+HedgeDoc 2, a PostgreSQL database and a Caddy reverse proxy.
+
+## Development or local testing
+
+To run HedgeDoc 2 locally, you do not need to change anything.
+Caddy will automatically generate a TLS certificate for `hedgedoc2.localhost` using its internal CA.  
+After running `docker compose up`, visit [https://hedgedoc2.localhost](https://hedgedoc2.localhost).
+You will have to accept the TLS warning in your browser the first time the page is opened.
+
+## Production setup
+
+!!! danger "HedgeDoc 2 is not yet production ready!"
+    This section explains how a production deployment of HedgeDoc 2 on a publicly accessible domain
+    might look in the future.  
+    HedgeDoc 2 itself is not production ready yet, so only use these instructions to set up an
+    instance for testing with your friends.
+
+For a production setup, first set a unique session secret with
+`sed -i "s/session_secret/$(pwgen -s 64)/" .env`.
+
+Then open the `.env` file and edit `HD_BASE_URL`. It needs to contain the full URL of your instance,
+like it will be entered in the browser. If you enter a URL starting with `https://`, Caddy will
+automatically gather certificates via *Let's Encrypt* (or its internal CA in case of `.localhost` domains).
+Make sure your host is accessible under the domain from `HD_BASE_URL`, otherwise Let's Encrypt
+validation will fail.
+
+Optionally, you can also change
+ 
+- `HD_MEDIA_BACKEND`: If you do not want HedgeDoc to handle media uploads itself, configure another backend
+  here. For more information, [see the media backend docs](/config/#media).
+- `HD_AUTH_*`: If you do not want to use the integrated auth system,
+  you can [consult the authentication docs](/config/#authentication) for details.

docs/mkdocs.yml

@@ -1,4 +1,4 @@
-site_name: HedgeDoc
+site_name: HedgeDoc 2
 site_url: https://docs.hedgedoc.org
 repo_url: https://github.com/hedgedoc/hedgedoc
 site_description: 'HedgeDoc Documentation'
@@ -7,6 +7,8 @@ docs_dir: content
 edit_uri: https://github.com/hedgedoc/hedgedoc/edit/master/docs/content/
 nav:
   - Home: index.md
+  - Installation:
+      - Getting Started: setup/getting_started.md
   - Configuration:
     - Configuration: config/index.md
     - Media: