Update hello_watchdog to detect reboot only by watchdog (#484)

Author: CorentinLemaitre

watchdog/hello_watchdog/hello_watchdog.c

@@ -11,7 +11,7 @@
 int main() {
     stdio_init_all();
 
-    if (watchdog_caused_reboot()) {
+    if (watchdog_enable_caused_reboot()) {
         printf("Rebooted by Watchdog!\n");
         return 0;
     } else {
@@ -30,4 +30,4 @@ int main() {
     // Wait in an infinite loop and don't update the watchdog so it reboots us
     printf("Waiting to be rebooted by watchdog\n");
     while(1);
-}
+}