Add datapipes deprecation warning banner to docs (#1312)

Co-authored-by: Andrew Ho <andrewkh@fb.com>

docs/source/conf.py

@@ -160,3 +160,16 @@ def setup(app):
 intersphinx_mapping = {
  "graphviz": ("https://graphviz.readthedocs.io/en/stable/", None),
 }
+
+rst_prolog = """.. attention::
+ **June 2024 Status Update: Removing DataPipes and DataLoader V2**
+
+ We are re-focusing the torchdata repo to be an iterative enhancement of torch.utils.data.DataLoader. We do not plan on
+ continuing development or maintaining the [`DataPipes`] and [`DataLoaderV2`] solutions, and they will be removed from
+ the torchdata repo. We'll also be revisiting the `DataPipes` references in pytorch/pytorch. In release
+ `torchdata==0.8.0` (July 2024) they will be marked as deprecated, and in 0.9.0 (Oct 2024) they will be deleted. Existing
+ users are advised to pin to `torchdata==0.8.0` or an older version until they are able to migrate away. Subsequent
+ releases will not include DataPipes or DataLoaderV2.
+ Please reach out if you suggestions or comments (please use `this issue <https://github.com/pytorch/data/issues/1196>`_ for feedback)
+
+"""