fix(docs): update broken MLX OpenAI Compatibility link (#538)

The mlx-lm server was moved from the mlx-examples repo to its own
ml-explore/mlx-lm repo. Update the link to point to the new location.

Fixes #438

Author: berry-13

content/docs/configuration/librechat_yaml/ai_endpoints/mlx.mdx

@@ -4,7 +4,7 @@ icon: MLX
 description: Example configuration for Apple MLX
 ---
 
-> [MLX OpenAI Compatibility](https://github.com/ml-explore/mlx-examples/blob/main/llms/mlx_lm/SERVER.md)
+> [MLX OpenAI Compatibility](https://github.com/ml-explore/mlx-lm/blob/main/mlx_lm/SERVER.md)
 
 **Notes:**