[Bugfix] Remove duplicated config keyword max batch size (#1851)

Signed-off-by: tzhouam <tzhouam@connect.ust.hk>
Signed-off-by: Zhou Taichang <tzhouam@connect.ust.hk>

docs/configuration/pd_disaggregation.md

@@ -32,8 +32,8 @@ stage_args:
     is_prefill_only: true
     runtime:
       devices: "0"
-      max_batch_size: 16
     engine_args:
+      max_num_seqs: 16
       model_stage: thinker
       model_arch: Qwen3OmniMoeForConditionalGeneration
       worker_type: ar
@@ -70,8 +70,8 @@ stage_args:
     is_decode_only: true
     runtime:
       devices: "1"
-      max_batch_size: 64
     engine_args:
+      max_num_seqs: 64
       model_stage: thinker
       model_arch: Qwen3OmniMoeForConditionalGeneration
       worker_type: ar
@@ -128,7 +128,8 @@ After inserting the extra thinker stage, renumber the remaining stages:
   - stage_id: 3
     runtime:
       devices: "2"
-      max_batch_size: 1
+    engine_args:
+      max_num_seqs: 1
     engine_input_source: [2]
     custom_process_input_func: vllm_omni.model_executor.stage_input_processors.qwen3_omni.talker2code2wav
 ```