Add sidequery to docs

Author: benbrandt

docs/overview/clients.mdx

@@ -12,3 +12,4 @@ The following clients can be used with an ACP Agent:
 - [neovim](https://neovim.io)
   - through the [CodeCompanion](https://github.com/olimorris/codecompanion.nvim) plugin
   - through the [yetone/avante.nvim](https://github.com/yetone/avante.nvim) plugin
+- [Sidequery _(coming soon)_](https://sidequery.dev)