Documented BIO_set_accept_port()/BIO_get_accept_port()

Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1386)

doc/crypto/BIO_s_accept.pod

@@ -15,7 +15,7 @@ BIO_set_bind_mode, BIO_get_bind_mode, BIO_do_accept - accept BIO
  long BIO_set_accept_name(BIO *b, char *name);
  char *BIO_get_accept_name(BIO *b);
 
- long BIO_set_accept_port(BIO *b, char *name);
+ long BIO_set_accept_port(BIO *b, char *port);
  char *BIO_get_accept_port(BIO *b);
 
  BIO *BIO_new_accept(char *host_port);
@@ -61,10 +61,16 @@ where "host" is the interface to use and "port" is the port.
 The host can be "*" or empty which is interpreted as meaning
 any interface.  If the host is an IPv6 address, it has to be
 enclosed in brackets, for example "[::1]:https".  "port" has the
-same syntax as the port specified in BIO_set_conn_name() for
+same syntax as the port specified in BIO_set_conn_port() for
 connect BIOs, that is it can be a numerical port string or a
 string to lookup using getservbyname() and a string table.
 
+BIO_set_accept_port() uses the string B<port> to set the accept
+port.  "port" has the same syntax as the port specified in
+BIO_set_conn_port() for connect BIOs, that is it can be a numerical
+port string or a string to lookup using getservbyname() and a string
+table.
+
 BIO_new_accept() combines BIO_new() and BIO_set_accept_name() into
 a single call: that is it creates a new accept BIO with port
 B<host_port>.
@@ -148,8 +154,9 @@ BIO_set_accept_name(), BIO_set_accept_port(), BIO_set_nbio_accept(),
 BIO_set_accept_bios(), and BIO_set_bind_mode(), return 1 for success and 0 or
 -1 for failure.
 
-BIO_set_accept_name() and BIO_get_accept_port() returns the port name or NULL
-on error.
+BIO_set_accept_name() returns the accept name or NULL on error.
+
+BIO_get_accept_port() returns the port as a string or NULL on error.
 
 BIO_get_bind_mode() returns the set of B<BIO_BIND> flags, or -1 on failure.