Reword what will happen with pointers outside the heap
Reword what will happen with pointers outside the heap

Following review comments.

Also: fix the assertion in the third val_of_typtr function.

gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml