Add in config for nushell (#406)

APP_CONFIG.md

@@ -26,6 +26,15 @@ Host *
 	IdentityAgent /Users/$YOUR_USERNAME/Library/Containers/com.maxgoedjen.Secretive.SecretAgent/Data/socket.ssh
 ```
 
+## nushell
+
+Add this to your `~/.ssh/config` (the path should match the socket path from the setup flow).
+
+```
+Host *
+	IdentityAgent /Users/$YOUR_USERNAME/Library/Containers/com.maxgoedjen.Secretive.SecretAgent/Data/socket.ssh
+```
+
 ## Cyberduck
 
 Add this to `~/Library/LaunchAgents/com.maxgoedjen.Secretive.SecretAgent.plist`