docs: clarify attention design coverage

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

docs/.nav.yml

@@ -50,7 +50,6 @@ nav:
       - Quantized KV Cache: user_guide/quantization/quantized_kvcache.md
       - FP8 W8A8: user_guide/quantization/fp8.md
       - Int8 W8A8: user_guide/quantization/int8.md
-      - BitsAndBytes W4: user_guide/quantization/bitsandbytes.md
       - MXFP8 W8A8: user_guide/quantization/mxfp8.md
       - MXFP4 W4A4: user_guide/quantization/mxfp4.md
       - ModelOpt: user_guide/quantization/modelopt.md
@@ -125,7 +124,7 @@ nav:
           - Sequence Parallel: design/feature/sequence_parallel.md
           - Tensor Parallel: design/feature/tensor_parallel.md
           - VAE Patch Parallelism: design/feature/vae_parallel.md
-        - Attention Backends:
+        - Attention Optimization:
           - Skip-Softmax: design/feature/skip_softmax.md
         - Cache-DiT: design/feature/cache_dit.md
         - TeaCache: design/feature/teacache.md

docs/design/index.md

@@ -50,7 +50,11 @@ implementation contract; it is not, by itself, a general support claim.
 - [Tensor Parallel](feature/tensor_parallel.md)
 - [VAE Patch Parallelism](feature/vae_parallel.md)
 
-#### Attention Backends
+#### Attention optimization
+
+The [Diffusion Attention Backends](../user_guide/diffusion/attention_backends.md)
+guide lists all selectable backends and their platform defaults. Skip-Softmax
+is the backend-related optimization with a standalone feature-design contract:
 
 - [Skip-Softmax](feature/skip_softmax.md)