Add instructions how to use home system's shell?

flatpak-warning.txt

@@ -14,6 +14,14 @@ to access SDKs on your host system!
 To execute commands on the host system, run inside the sandbox:
 
   $ flatpak-spawn --host <COMMAND>
+  
+To make the Integrated Terminal automatically use the host system's shell,
+you can add this to the settings:
+
+  {
+    "terminal.integrated.shell.linux": "/usr/bin/env",
+    "terminal.integrated.shellArgs.linux": ["--", "flatpak-spawn", "--host", "bash"]
+  }
 
 This flatpak provides a standard development environment (gcc, python, etc).
 To see what's available: