[drupal-docs] Tag handbook pages with major versions

[Karoly Negyesi]

Hi!

Let's create terms for each major version (DRUPAL-4-5, DRUPAL-4-6,  
DRUPAL-4-7...) and tag the handbook pages. There could be better, more  
comprehensive etc etc solutions but this has a big advantage: easy to  
implement. The handbook heads to uselessness as there are pages from 4.3  
to 4.7 and everything in between.

Regards

NK