[Doc] Cleanup non-english comments (#125)

Signed-off-by: Roger Wang <hey@rogerw.io>

docs/design/vllm_omni_design.md

@@ -449,15 +449,15 @@ AsyncLLM.add_request()
 ↓
 OutputProcessor.add_request()
 ↓
-RequestState.from_new_request() → 创建请求状态
+RequestState.from_new_request() → create request state
 
-AsyncLLM.__init__() / AsyncLLM.generate() / AsyncLLM.encode() →  创建一个Background loop 持续从EngineCore获取输出
+AsyncLLM.__init__() / AsyncLLM.generate() / AsyncLLM.encode() →  create a background loop that continuously pulls output from EngineCore
 ↓
-OutputProcessor.process_outputs() → 更新状态并处理输出
+OutputProcessor.process_outputs() → update state and process outputs
 ↓
-RequestState.make_request_output() → 转换为最终输出,格式为RequestOutput或者PoolingRequestOutput
+RequestState.make_request_output() → convert to the final output, formatted as RequestOutput or PoolingRequestOutput
 ↓
-RequestOutputCollector.put() → 推送到队列（AsyncLLM）
+RequestOutputCollector.put() → push to the queue (AsyncLLM)
 ```
 
 Need to add implementation for an existing method