update examples

examples/README.md

examples/README_zh.md

examples/extras/loraplus/sft.sh

examples/full_multi_gpu/predict.sh

examples/merge_lora/merge.sh

src/llmtuner/chat/vllm_engine.py

src/llmtuner/extras/packages.py

src/llmtuner/hparams/parser.py

src/llmtuner/model/loader.py

src/llmtuner/train/sft/metric.py

src/llmtuner/train/utils.py