docs: community feedback pixi global

Ask for community feedback in the design proposal

docs/design_proposals/pixi_global_manifest.md

@@ -1,5 +1,10 @@
 # Pixi Global Manifest
 
+!!! tip "Feedback wanted"
+
+    This document is work in progress, and community feedback is greatly appreciated.
+    https://github.com/prefix-dev/pixi/discussions/1799
+
 ## Motivation
 
 `pixi global` is currently limited to imperatively managing CLI packages.