(K)ubuntu changelog

The following information has been changed in the tutorial:

- Added explanation regarding article's validity over time
- Added comparison between KDE and GNOME environments
- Added mini table of contents with links to major chapters in the article
- Added sub-titles for major chapters in the article
- Added command to backup xorg before installation of graphic card drivers
- Added envy script as option for installation of graphic card drivers
- Added links to Edgy and Feisty Starter Guides
- Added links to psychocats.net and Kubuntu Desktop Guide
- Added links to some of my other Linux articles (including Linux command line tutorial)
- Added chapter about transition from Windows to Linux, with tips about codecs, java and flash
- Added chapter about most common KDE applications, with brief introduction to the most popular ones

- Fixed minor spelling mistakes
- Fixed minor phrasing and semantics errors