Legacy docs in new repository

[Upayavira]

I have just done a huge commit (sorry!) of the old 2.1 documentation, 
converted into a flat structure with the content formatted as HTML.

I've also committed a site.xml to go with this.
This means we're ready to start the job of moving content across to the 
new structure, bit by bit. I'll start on this in the next couple of 
days. Other volunteers welcome.

Regards, Upayavira