You should just copy Eater’s Wiki and then update it 
For me the Mythics and the Affixes pages have been the most useful.
Some info found only in the forum should be added too at some point, for example:
- crystal crafting restrictions (or put this info in an affixes table).
- items crafting guide.
- items conversions with Jaspers (there’s a nice pic somewhere).
- the damage formula (to understand which affixes to choose).
- Ascendent+Arcanist mandatory combo (why isn’t it clearly explained ingame yet?).
- Weaken, Ignore Resist, Effective detailed info.
- those annoying and complex stat caps (expecially exp\luck\gold\items).
- etc…