Cleanup readme, llava examples, usage examples and nccl init (#1194)

python/sglang/lang/chat_template.py

@@ -1,6 +1,6 @@
-from dataclasses import dataclass, field
+from dataclasses import dataclass
 from enum import Enum, auto
-from typing import Callable, Dict, List, Optional, Tuple
+from typing import Callable, Dict, List, Tuple
 
 
 class ChatTemplateStyle(Enum):