docs: Add docs for premium subscription

docs/docs/usage/premium.md

@@ -0,0 +1,27 @@
+---
+sidebar_position: 7
+---
+
+# Premium Subscription
+
+You can use the library to claim a premium subscription for your account. This will allow you to download videos in 1080p quality and access other premium features.
+
+```ts
+const { user } = await client.claimPremium();
+console.log('Claimed premium subscription for', user.name);
+```
+
+<details>
+    <summary>Output</summary>
+
+    ```bash
+    Claimed premium subscription for JokelBaf
+    ```
+
+</details>
+
+:::note
+
+Hanime API will raise 401 error if you try to claim premium with already active subscription, or without having enough coins. Make sure to handle this in your code properly.
+
+:::