[docs]: improve docs structure (#1623)

doc/SUMMARY.md

@@ -2,18 +2,19 @@
 
 [Introduction](./README.md)
 # Install & Usage
-- [For kt-kernel](en/kt-kernel_intro.md)
-- [For SFT](en/KTransformers-Fine-Tuning_User-Guide.md)
+- [For kt-kernel](en/kt-kernel/kt-kernel_intro.md)
+- [For SFT](en/SFT/KTransformers-Fine-Tuning_User-Guide.md)
 
 # Tutorial 
-## SFT part
+- [SFT part](en/SFT/README.md)
+  - [SFT developer tech notes](en/SFT/KTransformers-Fine-Tuning_Developer-Technical-Notes.md)
+  - [Injection Tutorial](en/injection_tutorial.md)
+  <!-- - [Multi-GPU Tutorial](en/multi-gpu-tutorial.md) -->
+  <!-- - [Use FP8 GPU Kernel](en/fp8_kernel.md) -->
+  <!-- - [Use AMD GPU](en/ROCm.md) -->
 <!-- - [Deepseek-R1/V3 Show Case/Tutorial](en/DeepseekR1_V3_tutorial.md) -->
 <!-- - [Why KTransformers So Fast](en/deepseek-v2-injection.md) -->
-- [Injection Tutorial](en/injection_tutorial.md)
-- [Multi-GPU Tutorial](en/multi-gpu-tutorial.md)
-- [Use FP8 GPU Kernel](en/fp8_kernel.md)
-- [Use AMD GPU](en/ROCm.md)
-- [SFT developer tech notes](en/KTransformers-Fine-Tuning_Developer-Technical-Notes.md)
+
 ## KT-kernel part
 <!-- # For Developer
 - [Makefile Usage](en/makefile_usage.md) -->

doc/en/SFT/README.md

@@ -0,0 +1 @@
+#SFT Docs

doc/en/kt-kernel/kt-kernel_intro.md

@@ -0,0 +1 @@
+../../../kt-kernel/README.md

doc/en/kt-kernel_intro.md

@@ -1 +0,0 @@
-../../kt-kernel/README.md