The best place is the official WDW webpage about Guests with Disabilities.
On the top of that page, there are links to each of the parks. The pages for the individual parks list each ride separately with a short description (very short, not very complete) and any restrictions for that particular attraction.
(There are also links to these references in the disABILITIES FAQs thread).
Also, when you get to the parks, the park maps have a little red triangle icon to mark those attractions that have restrictions. There is also a sign outside each attraction that lists any restrictions.