smol update to readme

Author: linoytsaban

examples/dreambooth/README_sd3.md

@@ -136,7 +136,7 @@ accelerate launch train_dreambooth_lora_sd3.py \
   --resolution=512 \
   --train_batch_size=1 \
   --gradient_accumulation_steps=4 \
-  --learning_rate=1e-5 \
+  --learning_rate=4e-4 \
   --report_to="wandb" \
   --lr_scheduler="constant" \
   --lr_warmup_steps=0 \