Doc fix

Reported by Alexander Köppe
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2557)

doc/man3/RSA_generate_key.pod

@@ -53,14 +53,15 @@ it is called as B<BN_GENCB_call(cb, 3, 0)>.
 
 The process is then repeated for prime q with B<BN_GENCB_call(cb, 3, 1)>.
 
-RSA_generate_key is deprecated (new applications should use
-RSA_generate_key_ex instead). RSA_generate_key works in the same way as
-RSA_generate_key_ex except it uses "old style" call backs. See
+RSA_generate_key() is deprecated (new applications should use
+RSA_generate_key_ex() instead). RSA_generate_key() works in the same way as
+RSA_generate_key_ex() except it uses "old style" call backs. See
 L<BN_generate_prime(3)> for further details.
 
 =head1 RETURN VALUE
 
-If key generation fails, RSA_generate_key() returns B<NULL>.
+RSA_generate_key_ex() returns 1 on success or 0 on error.
+RSA_generate_key() returns the key on success or B<NULL> on error.
 
 The error codes can be obtained by L<ERR_get_error(3)>.