add docs (#201)

add docs.

docs/source/GetStarted/Download_models.md

@@ -0,0 +1,20 @@
+# 下载模型
+
+下载预设模型，模型ID可参考 [config file](/diffsynth/configs/model_config.py).
+
+```python
+from diffsynth import download_models
+
+download_models(["FLUX.1-dev", "Kolors"])
+```
+
+下载非预设模型，可以选择 [ModelScope](https://modelscope.cn/models) 和 [HuggingFace](https://huggingface.co/models) 两个下载源中的模型。
+
+```python
+from diffsynth.models.downloader import download_from_huggingface, download_from_modelscope
+
+# From Modelscope (recommended)
+download_from_modelscope("Kwai-Kolors/Kolors", "vae/diffusion_pytorch_model.fp16.bin", "models/kolors/Kolors/vae")
+# From Huggingface
+download_from_huggingface("Kwai-Kolors/Kolors", "vae/diffusion_pytorch_model.fp16.safetensors", "models/kolors/Kolors/vae")
+```