Document SSL_CTX_set_min_proto_version defaults

If the function is not called the settings default to 0.

Fixes #10584

Signed-off-by: Norbert Pocs <norbertpocs0@gmail.com>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27410)

doc/man3/SSL_CTX_set_min_proto_version.pod

@@ -31,9 +31,10 @@ L<SSL_CTX_set_options(3)> that also make it possible to disable
 specific protocol versions.
 Use these functions instead of disabling specific protocol versions.
 
-Setting the minimum or maximum version to 0, will enable protocol
+Setting the minimum or maximum version to 0 (default), will enable protocol
 versions down to the lowest version, or up to the highest version
-supported by the library, respectively.
+supported by the library, respectively. The supported versions might be
+controlled by system configuration.
 
 Getters return 0 in case B<ctx> or B<ssl> have been configured to
 automatically use the lowest or highest version supported by the library.