add set time-zone and placeholder for serialconsole

docs/system/index.rst

@@ -14,7 +14,9 @@ should be ready for further configuration which is described in this chapter.
    eventhandler
    flowaccounting
    host-information
+   serialconsole
    systemusers
    syslog
    task-scheduler
-   config-management
+   config-management
+   time-zone

docs/system/serialconsole.rst

@@ -0,0 +1,17 @@
+.. _serial-console:
+
+Serial console
+==============
+
+
+
+Configuring Console
+-------------------
+
+.. code-block:: sh
+
+  vyos@vyos# set system console
+  Possible completions:
+  +> device       Serial console device name
+  +> network      Network based console logging
+     powersave    Enable screen blank powersaving on VGA console

docs/system/time-zone.rst

@@ -0,0 +1,11 @@
+.. _timezone:
+
+Time Zone
+=========
+
+To set the system time zone type:
+
+.. code-block:: sh
+
+  [edit]
+  vyos@vyos# set system time-zone [time-zone]