Improve the documentation for desktop and server mode configuration. Note what different config files are user for, and give an example of paths to override when setting up server mode.

docs/en_US/desktop_deployment.rst

@@ -20,6 +20,21 @@ In order to configure pgAdmin to run in desktop mode, it is first necessary to
 configure the Python code to run in single-user mode, and then to configure the
 runtime to find and execute the code.
 
+Note that there are multiple configuration files that are read at startup by
+pgAdmin. These are as follows:
+
+* ``config.py``: This is the main configuration file, and should not be modified.
+  It can be used as a reference for configuration settings, that may be overridden
+  in one of the following files.
+
+* ``config_distro.py``: This file is read after ``config.py`` and is intended for
+  packagers to change any settings that are required for their pgAdmin distribution.
+  This may typically include certain paths and file locations.
+
+* ``config_local.py``: This file is read after ``config_distro.py`` and is intended
+  for end users to change any default or packaging specific settings that they may
+  wish to adjust to meet local preferences or standards.
+
 Python
 ------
 
@@ -41,6 +56,9 @@ In order to configure the Python code, follow these steps:
    .. code-block:: bash
 
        $ python setup.py
+
+Alternatively, you can simply run ``pgAdmin4.py`` at this point or aat a later time,
+and ``pgadmin4.db`` will be created automatically at first run.
     
 Runtime
 -------