Wiki pages for the AIs

[Brumi]

With the growing number of AIs, I feel there is some need to have some wiki pages describing the AIs individually for the users. I went ahead and created a wiki page for SimpleAI: http://wiki.openttd.org/AI:SimpleAI
I linked this page from the AI comparison chart, and made it possible for further links to be added.

So with this I'm encouraging other AI authors to write a wiki page for their AIs as well WrightAI and Convoy already have pages from the old times.