Finish removing references to InstructDataset

Author: joecummings

docs/source/deep_dives/configs.rst

@@ -119,7 +119,7 @@ keyword arguments not specified in the config if we'd like:
         tokenizer: ModelTokenizer,
         train_on_input: bool = True,
         max_seq_len: int = 512,
-    ) -> InstructDataset:
+    ) -> SFTDataset:
 
     from torchtune import config
 

docs/source/tutorials/datasets.rst

@@ -495,10 +495,6 @@ that :class:`~torchtune.datasets.SFTDataset` and :class:`~torchtune.datasets.Tex
 you to create your own dataset class for more flexibility. Let's walk through the :class:`~torchtune.datasets.PreferenceDataset`,
 which has custom functionality for RLHF preference data, as an example to understand what you'll need to do.
 
-If you take a look at the code for the :class:`~torchtune.datasets.PreferenceDataset` class,
-you'll notice it's quite similar to :class:`~torchtune.datasets.InstructDataset` with a few
-adjustments for chosen and rejected samples in preference data.
-
 .. code-block:: python
 
     chosen_message = [