Add documentation for SSL version methods

[skip ci]
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3049)

doc/man3/SSL_get_version.pod

@@ -2,23 +2,33 @@
 
 =head1 NAME
 
-SSL_get_version, SSL_is_dtls - get the protocol information of a connection
+SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_version - get the
+protocol information of a connection
 
 =head1 SYNOPSIS
 
  #include <openssl/ssl.h>
 
+ int SSL_client_version(const SSL *s);
+
  const char *SSL_get_version(const SSL *ssl);
 
  int SSL_is_dtls(const SSL *ssl);
 
+ int SSL_version(const SSL *s);
+
 =head1 DESCRIPTION
 
+SSL_client_version() returns the protocol version used by the client when
+initiating the connection.
+
 SSL_get_version() returns the name of the protocol used for the
-connection B<ssl>.
+connection.
 
 SSL_is_dtls() returns one if the connection is using DTLS, zero if not.
 
+SSL_version() returns the protocol version used for the connection.
+
 =head1 RETURN VALUES
 
 SSL_get_version() returns one of the following strings:
@@ -41,12 +51,41 @@ The connection uses the TLSv1.1 protocol.
 
 The connection uses the TLSv1.2 protocol.
 
+=item TLSv1.3
+
+The connection uses the TLSv1.3 protocol.
+
 =item unknown
 
 This indicates that no version has been set (no connection established).
 
 =back
 
+SSL_version() and SSL_client_version() return an integer which could include any of
+the following:
+
+=over 5
+
+=item SSL3_VERSION
+
+The connection uses the SSLv3 protocol.
+
+=item TLS1_VERSION
+
+The connection uses the TLSv1.0 protocol.
+
+=item TLS1_1_VERSION
+
+The connection uses the TLSv1.1 protocol.
+
+=item TLS1_2_VERSION
+
+The connection uses the TLSv1.2 protocol.
+
+=item TLS1_3_VERSION
+
+The connection uses the TLSv1.3 protocol.
+
 =head1 SEE ALSO
 
 L<ssl(7)>
@@ -57,7 +96,7 @@ SSL_is_dtls() was added in OpenSSL 1.1.0.
 
 =head1 COPYRIGHT
 
-Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2001-2017 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the OpenSSL license (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy