Remove obsolete PRNG note. Add comment about use of SHA256 et al.

=head1 DESCRIPTION

SSL_library_init() registers the available ciphers and digests.

SSL_library_init() registers the available SSL/TLS ciphers and digests.

OpenSSL_add_ssl_algorithms() and SSLeay_add_ssl_algorithms() are synonyms

for SSL_library_init().

=head1 WARNING

SSL_library_init() only registers ciphers. Another important initialization

is the seeding of the PRNG (Pseudo Random Number Generator), which has to

be performed separately.

SSL_library_init() mainly adds ciphers and digests used directly by SSL/TLS.

In some cases this is not sufficient and errors about unknown algorithms

will occur: for example when an attempt is made to use a certificate using

SHA256. This can be resolved by also calling OpenSSL_add_all_algorithms().

=head1 EXAMPLES