esp8266: Change "soft reboot" message to work with pyboard.py.

esp8266/main.c

@@ -53,7 +53,7 @@ STATIC void mp_reset(void) {
 }
 
 void soft_reset(void) {
-    mp_hal_stdout_tx_str("PYB: soft reset\r\n");
+    mp_hal_stdout_tx_str("PYB: soft reboot\r\n");
     mp_hal_delay_us(10000); // allow UART to flush output
     mp_reset();
     pyexec_event_repl_init();