[Docs] Classify PD disaggregation as an experimental feature (#6115)

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>

mkdocs.yml

@@ -79,6 +79,7 @@ plugins:
         user_guide/diffusion/step_execution.md: user_guide/diffusion/execution_modes.md
         user_guide/diffusion/cpu_offload_diffusion.md: user_guide/diffusion/cpu_offload.md
         user_guide/quantization/index.md: user_guide/quantization/overview.md
+        configuration/pd_disaggregation.md: features/pd_disaggregation.md
         design/feature/diffusion_request_level_batching.md: design/feature/diffusion_continuous_batching.md
         design/feature/diffusion_step_execution.md: design/feature/diffusion_continuous_batching.md
         design/feature/cpu_offloading.md: design/feature/offloader/README.md