Not off hand I don't, but if you're looking for guidance or are interested in designing a site for people with learning disabilities, some general rules of thumb might help. Learning difficulties is a broad term; more of a politically correct way of giving a name to a very broad range of conditions; rather than a meaningful definition of something.
So, you can't really turn to "websites that are aimed at a learning difficulty" but rather, something more specific and may even lead you to sites that aren't aimed at a learning difficulty but something like an age group.
For example I have a family member who has a learning difficulty; he is intellectually about 8 years old and he finds websites targeted at children within that age range to be very easy to use and struggles with websites aimed at an older audience. He reads the kind of content a child would read more digestible than what a late teen/early twenties would read; in fact while he could read most of the words he wouldn't understand all of the content and would get bored a lot faster than an adult would.
So if I were designing a site that was aimed at people with a learning difficulty that has attributes similar to his; whereby they were mentally a child; I would for example check sites aimed at children; for example the CBBC websites; he spends quite a bit of time on those and uses them pretty well. Maybe take design principals from websites that are aimed at that age group.
What you should do will depend very much on the target audience; as it does with any design; and understanding the characteristics of a specific disability or learning difficulty and how they apply to a more general audience is really important.
General things such as these may help:
- Be clear, short and simple in any text
- Make good use of easy to understand, simple illustrations and info-graphics
- Make sure your UI and navigation is simple
- Make use of icons and graphics within your UI that will be easy to understand for your audience