gnome-panel strings change

[Sebastien Bacher]

Hi,

I've just updated update the System,Help submenu items according to bug
#31775, those strings are new and to translate:
- "Online Documentation"
- "Find more documentation online"
- "Community Support"
- "Get help from other Ubuntu users"
- "Commercial Support"
- "Find a commercial support provider"
- "Ubuntu Book Excerpt"
- "Read selected book chapters"


Cheers,

Sebastien Bacher