[docs] fix Quickstart 'What’s next?' links

Author: Dhiraj309

docs/source/quickstart.mdx

@@ -148,11 +148,10 @@ The optimizer type will be `<class 'bitsandbytes.optim.adam.Adam8bit'>`, and sta
 
 ## What’s next?
 
-* [Get started](./introduction)
-* [Installation](./installation)
-* [Quickstart](./quickstart)
-* [Usage Guides](./usage)
-* [8-bit optimizers](./optimizers/overview)
+- [Get started](index.mdx)
+- [Installation](installation.mdx)
+- [Quickstart](quickstart.mdx)
+- [8-bit optimizers](optimizers.mdx)
 
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