[Types] pointer spec should link to the gc #wontfix list

[crazymonkyyy]

https://forum.dlang.org/thread/ewztzzyxhvtyydmedxeb@forum.dlang.org

https://dlang.org/spec/type.html#pointers

https://dlang.org/spec/garbage.html#pointers_and_gc

apparently the gc #wontfix list isnt known at all, but its there having lots of opinions of how pointers should be used with the big scary words "UB"

[crazymonkyyy]

also the whole off by 1 thing from c should probably be clarified