[Xfce-i18n] Updating Translator-credits on the website and in xfce4-about

[Stephan Arts]

Hi everyone,

We are only hours away from the 'offical' release-announcement for
xfce 4.6 beta1.

Before the next release (beta2), I want to make sure the 'credits'
page on the website and in the xfce4-about dialog are up-to-date.

Because it is nearly impossible to check over 600 translation-files, I
want to ask you to tell us when your name is missing from the CREDITS
and we'll make sure to add them accordingly.

Kind regards,

Stephan