Update all URLs in example comments

Some of the URLs were broken.

Almost all of the URLs had changed, but were still working due to redirects. However, these redirects might stop working
at some time in the future (as happened during the last round of website reorganization) so it's safest to point them to
the final location.

Author: per1234

examples/01.Basics/Blink/Blink.ino

@@ -19,7 +19,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/Blink
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Blink
 */
 
 // the setup function runs once when you press reset or power the board

examples/01.Basics/DigitalReadSerial/DigitalReadSerial.ino

@@ -5,7 +5,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/DigitalReadSerial
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/DigitalReadSerial
 */
 
 // digital pin 2 has a pushbutton attached to it. Give it a name:

examples/01.Basics/Fade/Fade.ino

@@ -10,7 +10,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/Fade
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Fade
 */
 
 int led = 9;           // the PWM pin the LED is attached to

examples/01.Basics/ReadAnalogVoltage/ReadAnalogVoltage.ino

@@ -7,7 +7,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/ReadAnalogVoltage
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/ReadAnalogVoltage
 */
 
 // the setup routine runs once when you press reset:

examples/02.Digital/BlinkWithoutDelay/BlinkWithoutDelay.ino

@@ -25,7 +25,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/BlinkWithoutDelay
 */
 
 // constants won't change. Used here to set a pin number:

examples/02.Digital/Button/Button.ino

@@ -19,7 +19,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/Button
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Button
 */
 
 // constants won't change. They're used here to set pin numbers:

examples/02.Digital/Debounce/Debounce.ino

@@ -24,7 +24,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/Debounce
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Debounce
 */
 
 // constants won't change. They're used here to set pin numbers:

examples/02.Digital/DigitalInputPullup/DigitalInputPullup.ino

@@ -17,7 +17,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/InputPullupSerial
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/InputPullupSerial
 */
 
 void setup() {

examples/02.Digital/StateChangeDetection/StateChangeDetection.ino

@@ -21,7 +21,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/ButtonStateChange
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/StateChangeDetection
 */
 
 // this constant won't change:

examples/02.Digital/toneKeyboard/toneKeyboard.ino

@@ -14,7 +14,7 @@
 
   This example code is in the public domain.
 
-  http://www.arduino.cc/en/Tutorial/Tone3
+  https://www.arduino.cc/en/Tutorial/BuiltInExamples/toneKeyboard
 */
 
 #include "pitches.h"