Add un-used notice and PR template (#2069)

Author: albanD

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,15 @@
+> [!WARNING]
+> **This repository is NOT the source of truth for the PyTorch website.**
+> Only a very small number of files here are still actively used. Please do not submit website changes to this repo.
+>
+> See the [README](../README.md) for details, or contact the PyTorch Foundation team at [ops@pytorch.org](mailto:ops@pytorch.org).
+
+---
+
+**If your change is to one of the few files still served from this repo**, please describe it below:
+
+## Description
+
+
+## Motivation
+

README.md

@@ -1,3 +1,10 @@
+> [!CAUTION]
+> **This repository is NOT the source of truth for the [PyTorch website](https://pytorch.org).**
+>
+> Only a very small number of files in this repo are still actively used. The website is now managed separately by the **PyTorch Foundation** team.
+>
+> **If you want to make changes to the PyTorch website, please contact the PyTorch Foundation team at [ops@pytorch.org](mailto:ops@pytorch.org).** Do not open pull requests here for website changes.
+
 # pytorch.org site
 
 [https://pytorch.org](https://pytorch.org)