doc/man3/X509_STORE_get0_param.pod: mention how to free the returned objects

doc/man3/X509_STORE_get0_param.pod: mention how to free the returned objects

It is not entirely obvious from the description how the objects returned
by X509_STORE_get1_objects() and X509_STORE_get1_all_certs() are
supposed to be freed, explicitly mention the relevant calls, and provide
a reference to DEFINE_STACK_OF(3).

Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/29002)