Update README_sdxl.md to correct the header (huggingface#4330)

Update README_sdxl.md

Author: sayakpaul

examples/controlnet/README_sdxl.md

@@ -1,6 +1,6 @@
-# DreamBooth training example for Stable Diffusion XL (SDXL)
+# ControlNet training example for Stable Diffusion XL (SDXL)
 
-The `train_controlnet_sdxl.py` script shows how to implement the training procedure and adapt it for [Stable Diffusion XL](https://huggingface.co/papers/2307.01952).
+The `train_controlnet_sdxl.py` script shows how to implement the ControlNet training procedure and adapt it for [Stable Diffusion XL](https://huggingface.co/papers/2307.01952).
 
 ## Running locally with PyTorch
 
@@ -128,4 +128,4 @@ image.save("./output.png")
 
 ### Specifying a better VAE
 
-SDXL's VAE is known to suffer from numerical instability issues. This is why we also expose a CLI argument namely `--pretrained_vae_model_name_or_path` that lets you specify the location of a better VAE (such as [this one](https://huggingface.co/madebyollin/sdxl-vae-fp16-fix)).
+SDXL's VAE is known to suffer from numerical instability issues. This is why we also expose a CLI argument namely `--pretrained_vae_model_name_or_path` that lets you specify the location of a better VAE (such as [this one](https://huggingface.co/madebyollin/sdxl-vae-fp16-fix)).