[dLLM] Make FDFO a framework capability for all dLLM algorithms (#27551)

Co-authored-by: Xiaoyu Zhang <1182563586@qq.com>

docs_new/docs/supported-models/diffusion_language_models.mdx

@@ -16,6 +16,19 @@ python3 -m sglang.launch_server \
   --port 30000
 ```
 
+## First-Done-First-Out (FDFO) Scheduling
+
+FDFO scheduling is **enabled by default**: each request leaves the batch as soon as its block is resolved, instead of advancing in lockstep where fast-converging requests must wait for slow long-tail requests before leaving the batch (head-of-line blocking). This improves throughput and is orthogonal to `--dllm-algorithm`, so it works with any dLLM algorithm. Pass `--no-dllm-fdfo` to fall back to synchronous lockstep scheduling:
+
+```bash Command
+python3 -m sglang.launch_server \
+  --model-path inclusionAI/LLaDA2.0-mini \
+  --dllm-algorithm LowConfidence \
+  --no-dllm-fdfo \
+  --host 0.0.0.0 \
+  --port 30000
+```
+
 ## Example Configuration File
 
 Depending on the algorithm selected, the configuration parameters vary.