Add information on security expectations with this software (#6941)

Inspired by the link vllm
[includes](https://github.com/vllm-project/vllm/blob/main/SECURITY.md),
this starts to give users insight into the security expectations they
should have from using DeepSpeed.

SECURITY.md

@@ -39,3 +39,7 @@ We prefer all communications to be in English.
 Microsoft follows the principle of [Coordinated Vulnerability Disclosure](https://www.microsoft.com/en-us/msrc/cvd).
 
 <!-- END MICROSOFT SECURITY.MD BLOCK -->
+
+---
+
+Please see [PyTorch's Security Policy](https://github.com/pytorch/pytorch/blob/main/SECURITY.md) for more information and recommendations on how to securely interact with models.