Document config location

Author: akb

README.rst

@@ -310,9 +310,28 @@ For example, the ``3 seconds`` item is ready before the preceding ``4 seconds``
 Configuration
 ~~~~~~~~~~~~~
 
-Add code to automatically execute, into your config file.
+The config file location follows the `freedesktop.org standard <https://www.freedesktop.org/wiki/Software/xdg-user-dirs/>`_. Check the location on your system by running ``mario --help``:
+
+
+.. code-block:: bash
+
+    % mario --help
+    Usage: mario [OPTIONS] COMMAND1 [ARGS]... [COMMAND2 [ARGS]...]...
+
+      Mario: Python pipelines for your shell.
+
+      GitHub: https://github.com/python-mario/mario
+
+      Configuration:
+        Declarative config: /home/user/.config/mario/config.toml
+        Python modules: /home/user/.config/mario/modules/*.py
+
+
+
+
+For example on Ubuntu we use ``~/.config/mario/config.toml`` for declarative configuration. Add code and settings into your config.
+
 
-For example:
 
 .. code-block:: toml