checkdoc-ispell-docstring-engine

checkdoc-ispell-docstring-engine is a compiled Lisp function in `checkdoc.el'.

(checkdoc-ispell-docstring-engine END)

Run the Ispell tools on the doc string between point and END.
Since Ispell isn't Lisp-smart, we must pre-process the doc string
before using the Ispell engine on it.