BIO_new_bio_pair() was unnecessarily described in it's own page as well as in

BIO_s_bio.pod.  The most logical is to move everything needed from
BIO_new_bio_pair.pod to BIO_s_bio.pod (including the nice example)
and toss BIO_new_bio_pair.pod.  I hope I got all the info over properly.
PR: 370