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   |