[docs] typo : corrected 'compile regions' to 'compile_regions' (#12199)

[docs] typo: corrected 'compile regions' to 'compile_regions'

docs/source/en/optimization/fp16.md

@@ -209,7 +209,7 @@ There is also a [compile_regions](https://github.com/huggingface/accelerate/blob
 # pip install -U accelerate
 import torch
 from diffusers import StableDiffusionXLPipeline
-from accelerate.utils import compile regions
+from accelerate.utils import compile_regions
 
 pipeline = StableDiffusionXLPipeline.from_pretrained(
     "stabilityai/stable-diffusion-xl-base-1.0", torch_dtype=torch.float16