make avante public and add note about codegate.nvim

Author: kantord

docs/integrations/avante.mdx

@@ -17,6 +17,14 @@ through Avante.
 You can also use [CodeGate muxing](../features/muxing.mdx) to select your
 provider and model using [workspaces](../features/workspaces.mdx).
 
+:::note
+
+You can **additionally** install
+[codegate.nvim](https://github.com/stacklok/codegate.nvim), which will provide a
+closer integration with CodeGate.
+
+:::
+
 ## Install avante.nvim
 
 Install the `avante.nvim` plugin using your preferred Neovim plugin manager. For