Demote log message to info.

This log is harmless, and can be common at relays if clients are sending XOFF.

src/core/mainloop/mainloop.c

@@ -644,7 +644,7 @@ connection_start_reading,(connection_t *conn))
     if (CONN_IS_EDGE(conn) && TO_EDGE_CONN(conn)->xoff_received) {
       /* We should not get called here if we're waiting for an XON, but
        * belt-and-suspenders */
-      log_notice(LD_NET,
+      log_info(LD_NET,
                "Request to start reading on an edgeconn blocked with XOFF");
       return;
     }