Update acpt.md to fix docs sidebar

ACPT docs should be nested inside Ecosystem category in the docs sidebar, but they currently show up outside of the category at the top of the sidebar.

Need to add parent to address this issue.

docs/ecosystem/acpt.md

@@ -1,6 +1,7 @@
 ---
 title: Azure Container for PyTorch (ACPT)
 description: Learn more about Azure Container for PyTorch (ACPT) and how it utilizes ONNX Runtime
+parent: Ecosystem
 nav_order: 1
 redirect_from: /docs/tutorials/ecosystem/acpt
 ---