Clarify a few more comments and documentation
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 8e3161c..653f857 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1337,7 +1337,8 @@
 
 /**
  * \brief           Set the transport type (TLS or DTLS).
- *                  Default: TLS if both are enabled, or DTLS.
+ *                  Default: TLS if #MBEDTLS_SSL_PROTO_TLS is defined, else
+ *                  DTLS.
  *
  * \note            For DTLS, you must either provide a recv callback that
  *                  doesn't block, or one that handles timeouts, see