Added "Unmanaged Configurations" instructions to README #16

Removed deprecated "Default Configuration"; closes #16

README.rst

@@ -58,7 +58,7 @@ UCI configuration options must go in ``/etc/config/openwisp``.
 - ``uuid``: unique identifier of the router configuration in the controller application
 - ``key``: key required to download the configuration
 - ``shared_secret``: shared secret, needed for `Automatic registration`_
-- ``merge_default``: list of default configuration files that must be kept, see `Default Configuration`_
+- ``unmanaged``: list of config sections which won't be overwritten, see `Unmanaged Configurations`_
 - ``test_config``: whether a new configuration must be tested before being considered applied, defaults to ``1``
 - ``test_script``: custom test script, read more about this feature in `Configuration test`_
 
@@ -101,39 +101,41 @@ If the default test does not satisfy your needs, you can define your own tests i
 
 If the exit code of the executable script is higher than ``0`` the test will be considered failed.
 
-Default Configuration
----------------------
+Unmanaged Configurations
+------------------------
 
-In some cases it is necessary to ensure that some configuration files won't be
+In some cases it is necessary to ensure that some configuration sections won't be
 overwritten by the controller.
 
-These configuration files will be backed up the first time the agent will be able
-to contact the controller (which means it will have a basic working configuration.) and
-from then on they will be merged in after the configuration is downloaded and applied.
-
-This also allows you to avoid to define a lot of boilerplate configuration in the controller,
-think about LED settings, switch directives, NTP configuration and so on.
+This brings two main advantages:
 
-When *openwisp-config* is installed the following packages are listed in ``merge_default``:
+- it frees you from defining a lot of boilerplate configuration in the controller,
+  think about LED settings, switch directives, NTP configuration and so on
+- it allows you to define settings that can be managed manually via luci/SSH when needed,
+  think about a user wanting to change its LAN ip settings from dhcp to a precise static address
 
-* ``system``
-* ``network``
-
-Eg::
+These are the default unmanaged settings::
 
     config controller 'http'
             ...
-            list merge_default 'system'
-            list merge_default 'network'
+            list unmanaged 'system.ntp'
+            list unmanaged 'system.@led'
+            list unmanaged 'network.loopback'
+            list unmanaged 'network.globals'
+            list unmanaged 'network.lan'
+            list unmanaged 'network.wan'
+            list unmanaged 'network.@switch'
+            list unmanaged 'network.@switch_vlan'
             ...
 
-The ``system`` config file is treated in a special way: ``hostname`` and ``timezone`` are
-removed because they are always automatically generated by the controller.
+Note the lines with the `@` sign; that syntax means that any UCI section of that type will be unmanaged.
+
+All the other lines refer to precise named UCI settings, eg: ``network.lan`` refers to the LAN interface.
 
-Disable default configuration
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Disable Unmanaged Configurations
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-To disable this feature, just remove all the ``merge_default`` options.
+To disable unmanaged configurations simply remove all the ``unmanaged`` options.
 
 Compiling openwisp-config
 -------------------------