Feat: Improve Docs (#1791)

* improve docs

* preplan guides

* fix spelling

* fix nftables rules

* consistent wg-easy code block

* fix grammar

docs/content/advanced/api.md

@@ -2,4 +2,37 @@
 title: API
 ---
 
-TODO
+You can use the API to interact with the application programmatically. The API is available at `/api` and supports both GET and POST requests. The API is designed to be simple and easy to use, with a focus on providing a consistent interface for all endpoints.
+
+There is no documentation for the API yet, but this will be added as the underlying library supports it.
+
+## Authentication
+
+To use the API, you need to authenticate using Basic Authentication. The username and password are the same as the ones you use to log in to the web application.
+If you use 2FA, the API will not work. You need to disable 2FA in the web application to use the API.
+
+### Authentication Example
+
+```python
+import requests
+from requests.auth import HTTPBasicAuth
+
+url = "https://example.com:51821/api/client"
+response = requests.get(url, auth=HTTPBasicAuth('username', 'password'))
+if response.status_code == 200:
+    data = response.json()
+    print(data)
+else:
+    print(f"Error: {response.status_code}")
+```
+
+## Endpoints
+
+The Endpoints are not yet documented. But as file-based routing is used, you can find the endpoints in the `src/server/api` folder. The method is defined in the file name.
+
+### Endpoints Example
+
+| File Name                        | Endpoint       | Method |
+| -------------------------------- | -------------- | ------ |
+| `src/server/api/client.get.ts`   | `/api/client`  | GET    |
+| `src/server/api/setup/2.post.ts` | `/api/setup/2` | POST   |

docs/content/advanced/config/optional-config.md

@@ -2,7 +2,7 @@
 title: Optional Configuration
 ---
 
-TODO
+You can set these environment variables to configure the container. They are not required, but can be useful in some cases.
 
 | Env        | Default   | Example     | Description                    |
 | ---------- | --------- | ----------- | ------------------------------ |

docs/content/advanced/config/unattended-setup.md

@@ -26,7 +26,7 @@ If you want to skip the setup process, you have to configure group `1`
 
 /// note | Security
 
-The initial username and password is not checked for complexity. Make sure to set a long enough username and a secure password. Otherwise, the user won't be able to log in.
+The initial username and password is not checked for complexity. Make sure to set a long enough username and password. Otherwise, the user won't be able to log in.
 
-Its recommended to remove the variables after the setup is done to prevent the password from being exposed.
+It's recommended to remove the variables after the setup is done to prevent the password from being exposed.
 ///

docs/content/advanced/metrics/prometheus.md

@@ -2,6 +2,41 @@
 title: Prometheus
 ---
 
-TODO
+To monitor the WireGuard server, you can use [Prometheus](https://prometheus.io/) and [Grafana](https://grafana.com/). The container exposes a `/metrics/prometheus` endpoint that can be scraped by Prometheus.
 
-<!-- TOOD: add to docs: Grafana dashboard [21733](https://grafana.com/grafana/dashboards/21733-wireguard/) -->
+## Enable Prometheus
+
+To enable Prometheus metrics, go to Admin Panel > General and enable Prometheus.
+
+You can optionally set a Bearer Password for the metrics endpoints. This is useful if you want to expose the metrics endpoint to the internet.
+
+## Configure Prometheus
+
+You need to add a scrape config to your Prometheus configuration file. Here is an example:
+
+```yaml
+scrape_configs:
+  - job_name: "wg-easy"
+    scrape_interval: 30s
+    metrics_path: /metrics/prometheus
+    static_configs:
+      - targets:
+          - "localhost:51821"
+    authorization:
+      type: Bearer
+      credentials: "SuperSecurePassword"
+```
+
+## Grafana Dashboard
+
+You can use the following Grafana dashboard to visualize the metrics:
+
+[![Grafana Dashboard](https://grafana.com/api/dashboards/21733/images/16863/image)](https://grafana.com/grafana/dashboards/21733-wireguard/)
+
+[21733](https://grafana.com/grafana/dashboards/21733-wireguard/)
+
+/// note | Unofficial
+
+The Grafana dashboard is not official and is not maintained by the `wg-easy` team. If you have any issues with the dashboard, please contact the author of the dashboard.
+See [#1299](https://github.com/wg-easy/wg-easy/pull/1299) for more information.
+///