[docs] Cleanup homepage (#2823)

Author: Phlip79

docs/index.md

@@ -13,65 +13,3 @@ Megatron Core offers a flexible, reusable foundation for building large-scale tr
 * GPU-optimized kernels and memory management
 * High-performance dataloaders and dataset utilities
 * Model architectures (LLaMA, Qwen, DeepSeek, GPT, Mamba, etc.)
-
-```{toctree}
-:maxdepth: 2
-:caption: Get Started
-
-get-started/quickstart
-```
-
-```{toctree}
-:maxdepth: 2
-:caption: Basic Usage
-
-user-guide/data-preparation
-user-guide/training-examples
-user-guide/parallelism-guide
-```
-
-```{toctree}
-:maxdepth: 2
-:caption: Supported Models
-
-models/index
-```
-
-```{toctree}
-:maxdepth: 2
-:caption: Advanced Features
-
-user-guide/features/moe
-user-guide/features/context_parallel
-user-guide/features/custom_fsdp
-user-guide/features/dist_optimizer
-user-guide/features/optimizer_cpu_offload
-user-guide/features/pipeline_parallel_layout
-user-guide/features/megatron_energon
-user-guide/features/megatron_rl
-user-guide/features/tokenizers
-```
-
-```{toctree}
-:maxdepth: 1
-:caption: Developer Guide
-
-developer/contribute
-developer/submit
-developer/oncall
-```
-
-```{toctree}
-:maxdepth: 2
-:caption: Discussions
-
-advanced/index
-```
-
-```{toctree}
-:maxdepth: 2
-:caption: API Reference
-
-api-guide/index
-apidocs/index.rst
-```