In bio.h rev. 1.34 2018/02/20 17:15:27, jsing@ provided

In bio.h rev. 1.34 2018/02/20 17:15:27, jsing@ provided
BIO_get_new_index(3), in rev. 1.37 2018/02/20 18:13:31, tb@ provided
BIO_meth_get_read(3), BIO_meth_get_puts(3), BIO_meth_get_gets(3),
BIO_meth_get_ctrl(3), BIO_meth_get_create(3), and BIO_meth_get_destroy(3),
and in rev. 1.38 2018/02/20 18:17:17 BIO_meth_get_callback_ctrl(3)
and BIO_meth_set_callback_ctrl(3).
BIO_meth_get_write(3) will become public with the next minor bump.
Merge the documentation from OpenSSL, tweaked by me, OK tb@.