Add EEPROM debug printouts, error check to example (#6556)

* Add EEPROM debug printouts, error check to example

Add debug printouts when EEPROM calls fail, even if the API doesn't
allow returning a success/failure code.

Adds error checking to the example to make it explicit that when you
call EEPROM::commit(), you need to look at the result code in your code.

Fixes #6551 , or would fix it if there was error checking in the MCVE.

* Clarify example error message

libraries/EEPROM/examples/eeprom_read/eeprom_read.ino

@@ -14,7 +14,7 @@ byte value;
 
 void setup() {
   // initialize serial and wait for port to open:
-  Serial.begin(9600);
+  Serial.begin(115200);
   while (!Serial) {
     ; // wait for serial port to connect. Needed for Leonardo only
   }

libraries/EEPROM/examples/eeprom_write/eeprom_write.ino

@@ -13,6 +13,7 @@
 int addr = 0;
 
 void setup() {
+  Serial.begin(115200);
   EEPROM.begin(512);
 }
 
@@ -33,7 +34,11 @@ void loop() {
   addr = addr + 1;
   if (addr == 512) {
     addr = 0;
-    EEPROM.commit();
+    if (EEPROM.commit()) {
+      Serial.println("EEPROM successfully committed");
+    } else {
+      Serial.println("ERROR! EEPROM commit failed");
+    }
   }
 
   delay(100);