Update the location of the pod files

CLA: trivial
Since 99d63d46 ("Move manpages to man[1357] structure.", 2016-10-26), the location
of the pod files has changed.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1951)