Inspired by issue issue8973, I did
$ grep -in "see.*\.__doc__" Modules/*.c
Surprisingly, there were not as many results as I feared.
As I explained in the referenced issue, "See name.__doc__", while technically correct, is not user friendly. If you copy name.__doc__ to >>> prompt, you get an ugly repr of a multiline string. I suggest s/name.__doc__/help(struct)/.
Here are the grep results
Modules/_threadmodule.c:904:Create a new lock object. See LockType.__doc__ for information about locks.");
Modules/pwdmodule.c:103:See pwd.__doc__ for more on password database entries.");
Modules/pwdmodule.c:124:See pwd.__doc__ for more on password database entries.");
Modules/pwdmodule.c:155:See pwd.__doc__ for more on password database entries.");
Modules/spwdmodule.c:111:See spwd.__doc__ for more on shadow password database entries.");
Modules/spwdmodule.c:143:See spwd.__doc__ for more on shadow password database entries.");