Document remaining obsolete SSL_OP_NETSCAPE_*_BUG

Document remaining obsolete SSL_OP_NETSCAPE_*_BUG

SSL_OP_NETSCAPE_CA_DN_BUG became obsolete in 3c33c6f6b1086435 and
support for SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG was removed by
7a4dadc3a6a487db. The definitions are still listed under "OBSOLETE
OPTIONS retained for compatibility" in ssl.h.in, so this commit adds
them to the list of obsolete options in doc/man3.

Refs: https://github.com/nodejs/node/pull/46954

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20443)