nginx: Fix incorrect display of YAML config example in documentation (#2119)

nginx_proxy/DOCS.md

@@ -14,16 +14,18 @@ The NGINX Proxy add-on is commonly used in conjunction with the [Duck DNS](https
 
 1. The certificate to your registered domain should already be created via the [Duck DNS](https://github.com/home-assistant/hassio-addons/tree/master/duckdns) add-on or another method. Make sure that the certificate files exist in the `/ssl` directory.
 2. In the `configuration.yaml` file, some options in the `http:` section are no longer necessary for this scenario, and should be commented out or removed:
-    - `ssl_certificate`
-    - `ssl_key`
-    - `server_port`
+  - `ssl_certificate`
+  - `ssl_key`
+  - `server_port`
 3. And you need to add the `trusted_proxies` section (requests from reverse proxies will be blocked if these options are not set).
-```yaml
-http:
-  use_x_forwarded_for: true
-  trusted_proxies:
-    - 172.30.33.0/24
-```
+
+  ```yaml
+  http:
+    use_x_forwarded_for: true
+    trusted_proxies:
+      - 172.30.33.0/24
+  ```
+
 4. In the nginx addon configuration, change the `domain` option to the domain name you registered (from DuckDNS or any other domain you control).
 5. Leave all other options as-is.
 6. Save configuration.