Fix UserDTO Link

Author: CryptoGing

authentication.md

@@ -12,7 +12,7 @@ const authRes = await window.Pi.authenticate(scopes, onIncompletePaymentFound);
 ```
 
 ### 2. Make a GET request to `/me` Pi API endpoint using the access token for verification
-To verify the data you got in step 1, you need to make a GET request to `/me` Pi API endpoint, with the access token included in the header. If the access token is valid, it will return a response with [UserDTO](./platform_API#UserDTO). However, if the token is invalid, it will return HTTP 401 Unauthorized code.
+To verify the data you got in step 1, you need to make a GET request to `/me` Pi API endpoint, with the access token included in the header. If the access token is valid, it will return a response with [UserDTO](./platform_API.md#UserDTO). However, if the token is invalid, it will return HTTP 401 Unauthorized code.
 ```javascript
 const me = await axios.get('https://api.minepi.com/v2/me', {headers: {'Authorization': `Bearer ${accessToken}}});
-```
+```