Fix links in Placeholders and API Reference sections for correct navigation

Author: jesperrichert

docs/index.mdx

@@ -29,12 +29,12 @@ It is built with TypeScript and is designed to be modular, allowing for easy cus
 
 ## Placeholders
 
-- Take a look at the [Placeholders](placeholders) page to see all available placeholders.
+- Take a look at the [Placeholders](./placeholders.mdx) page to see all available placeholders.
 - Placeholders are used to replace certain values in messages, such as user IDs, usernames, and server names.
 
 ## API Reference
 
-- Take a look at the [API Reference](api) page to see all available API methods and events.
+- Take a look at the [API Reference](./api/index.mdx) page to see all available API methods and events.
 - Events API is used to listen to events in your server, such as member joins, leaves, and bans.
 
 ## Contact Us