#198 Document how to use Taurus GUIs lateral applet bar

[marc]

Document how to use Taurus lateral applet bar.

Taurus right lateral applet/widget bar in TaurusGUIs is not documented.

Documentation to be added in Taurus:

--
Widgets can be added to applet/widget bar by defining this lines in the config.py of the corresponding taurusgui:

cd = AppletDescription('CountDownWidget',
classname = 'countdown.CountDownWidget')

--