Update docs of unet_1d.py (huggingface#4394)

Update unet_1d.py

highlighting the way the modules are actually fed in the main code as the order matters because no skip block attaches time embeds whilst others do not

src/diffusers/models/unet_1d.py

@@ -56,9 +56,9 @@ class UNet1DModel(ModelMixin, ConfigMixin):
         freq_shift (`float`, *optional*, defaults to 0.0): Frequency shift for Fourier time embedding.
         flip_sin_to_cos (`bool`, *optional*, defaults to `False`):
             Whether to flip sin to cos for Fourier time embedding.
-        down_block_types (`Tuple[str]`, *optional*, defaults to `("DownBlock1D", "DownBlock1DNoSkip", "AttnDownBlock1D")`):
+        down_block_types (`Tuple[str]`, *optional*, defaults to `("DownBlock1DNoSkip", "DownBlock1D", "AttnDownBlock1D")`):
             Tuple of downsample block types.
-        up_block_types (`Tuple[str]`, *optional*, defaults to `("UpBlock1D", "UpBlock1DNoSkip", "AttnUpBlock1D")`):
+        up_block_types (`Tuple[str]`, *optional*, defaults to `("AttnUpBlock1D", "UpBlock1D", "UpBlock1DNoSkip")`):
             Tuple of upsample block types.
         block_out_channels (`Tuple[int]`, *optional*, defaults to `(32, 32, 64)`):
             Tuple of block output channels.