Rebase PyTorch guide on SHARK-Turbine. (#15181)

Fixes https://github.com/openxla/iree/issues/15114 (future work can be
tracked elsewhere, this does the initial lift).

This refreshes the docs from pointing to a mix of
[torch-mlir](https://github.com/llvm/torch-mlir) and
[iree-torch](https://github.com/iree-org/iree-torch) to just pointing to
[SHARK-Turbine](https://github.com/nod-ai/SHARK-Turbine). Turbine is
built on top of torch-mlir and IREE and is under active development.
* Turbine supports both JIT and AOT workflows, and this PR documents
both
* The "AOT toolkit" has a simple API and an advanced API, but I've only
documented the simple API in this first PR

---

|  | |
|--------|--------|
| Current page | https://www.iree.dev/guides/ml-frameworks/pytorch/ |
| Preview of this PR |
https://scotttodd.github.io/iree/guides/ml-frameworks/pytorch/ |

---

Depends on https://github.com/openxla/iree/pull/15166 for one sample
Colab notebook.
diff --git a/docs/website/mkdocs.yml b/docs/website/mkdocs.yml
index ca643c8..bcdc071 100644
--- a/docs/website/mkdocs.yml
+++ b/docs/website/mkdocs.yml
@@ -70,7 +70,7 @@
       name: IREE Discuss Google Group
 
   status:
-    new: Recently added
+    new: Recently updated
 
 extra_css:
   - assets/stylesheets/extra.css