[Model Card] standardize T2I Sdxl Lora model card (#6944)

* standardize model card template t2i-lora-sdxl

* type annotations

examples/text_to_image/train_text_to_image_lora_sdxl.py

@@ -58,6 +58,7 @@ from diffusers.utils import (
     convert_unet_state_dict_to_peft,
     is_wandb_available,
 )
+from diffusers.utils.hub_utils import load_or_create_model_card, populate_model_card
 from diffusers.utils.import_utils import is_xformers_available
 from diffusers.utils.torch_utils import is_compiled_module
 
@@ -70,33 +71,20 @@ logger = get_logger(__name__)
 
 def save_model_card(
     repo_id: str,
-    images=None,
-    base_model=str,
-    dataset_name=str,
-    train_text_encoder=False,
-    repo_folder=None,
-    vae_path=None,
+    images: list = None,
+    base_model: str = None,
+    dataset_name: str = None,
+    train_text_encoder: bool = False,
+    repo_folder: str = None,
+    vae_path: str = None,
 ):
     img_str = ""
-    for i, image in enumerate(images):
-        image.save(os.path.join(repo_folder, f"image_{i}.png"))
-        img_str += f"![img_{i}](./image_{i}.png)\n"
+    if images is not None:
+        for i, image in enumerate(images):
+            image.save(os.path.join(repo_folder, f"image_{i}.png"))
+            img_str += f"![img_{i}](./image_{i}.png)\n"
 
-    yaml = f"""
----
-license: creativeml-openrail-m
-base_model: {base_model}
-dataset: {dataset_name}
-tags:
-- stable-diffusion-xl
-- stable-diffusion-xl-diffusers
-- text-to-image
-- diffusers
-- lora
-inference: true
----
-    """
-    model_card = f"""
+    model_description = f"""
 # LoRA text2image fine-tuning - {repo_id}
 
 These are LoRA adaption weights for {base_model}. The weights were fine-tuned on the {dataset_name} dataset. You can find some example images in the following. \n
@@ -106,8 +94,19 @@ LoRA for the text encoder was enabled: {train_text_encoder}.
 
 Special VAE used for training: {vae_path}.
 """
-    with open(os.path.join(repo_folder, "README.md"), "w") as f:
-        f.write(yaml + model_card)
+    model_card = load_or_create_model_card(
+        repo_id_or_path=repo_id,
+        from_training=True,
+        license="creativeml-openrail-m",
+        base_model=base_model,
+        model_description=model_description,
+        inference=True,
+    )
+
+    tags = ["stable-diffusion-xl", "stable-diffusion-xl-diffusers", "text-to-image", "diffusers", "lora"]
+    model_card = populate_model_card(model_card, tags=tags)
+
+    model_card.save(os.path.join(repo_folder, "README.md"))
 
 
 def import_model_class_from_model_name_or_path(