Added WiFi.disconnect to ESPNow examples. Fixes...

Added WiFi.disconnect to ESPNow examples. Fixes https://github.com/espressif/arduino-esp32/issues/1425 (#1511)

libraries/ESP32/examples/ESPNow/Basic/Master/Master.ino

@@ -40,6 +40,7 @@ esp_now_peer_info_t slave;
 
 // Init ESP Now with fallback
 void InitESPNow() {
+  WiFi.disconnect();
   if (esp_now_init() == ESP_OK) {
     Serial.println("ESPNow Init Success");
   }

libraries/ESP32/examples/ESPNow/Basic/Slave/Slave.ino

@@ -36,6 +36,7 @@
 
 // Init ESP Now with fallback
 void InitESPNow() {
+  WiFi.disconnect();
   if (esp_now_init() == ESP_OK) {
     Serial.println("ESPNow Init Success");
   }

libraries/ESP32/examples/ESPNow/Multi-Slave/Master/Master.ino

@@ -59,6 +59,7 @@ int SlaveCnt = 0;
 
 // Init ESP Now with fallback
 void InitESPNow() {
+  WiFi.disconnect();
   if (esp_now_init() == ESP_OK) {
     Serial.println("ESPNow Init Success");
   }

libraries/ESP32/examples/ESPNow/Multi-Slave/Slave/Slave.ino

@@ -36,6 +36,7 @@
 
 // Init ESP Now with fallback
 void InitESPNow() {
+  WiFi.disconnect();
   if (esp_now_init() == ESP_OK) {
     Serial.println("ESPNow Init Success");
   }