Add current limiting resistors for LEDs to circuit description comments

I followed the existing precedent set in the "WhileStatementConditional" example for the text.

220 ohm is the value used in the tutorials for the examples, as well as being what is provided in the Starter Kit.

Author: per1234

examples/02.Digital/Button/Button.ino

@@ -5,7 +5,7 @@
   when pressing a pushbutton attached to pin 2.
 
   The circuit:
-  - LED attached from pin 13 to ground
+  - LED attached from pin 13 to ground through 220 ohm resistor
   - pushbutton attached to pin 2 from +5V
   - 10K resistor attached to pin 2 from ground
 

examples/02.Digital/Debounce/Debounce.ino

@@ -6,7 +6,7 @@
   minimum delay between toggles to debounce the circuit (i.e. to ignore noise).
 
   The circuit:
-  - LED attached from pin 13 to ground
+  - LED attached from pin 13 to ground through 220 ohm resistor
   - pushbutton attached from pin 2 to +5V
   - 10 kilohm resistor attached from pin 2 to ground
 

examples/02.Digital/StateChangeDetection/StateChangeDetection.ino

@@ -12,8 +12,8 @@
   The circuit:
   - pushbutton attached to pin 2 from +5V
   - 10 kilohm resistor attached to pin 2 from ground
-  - LED attached from pin 13 to ground (or use the built-in LED on most
-    Arduino boards)
+  - LED attached from pin 13 to ground through 220 ohm resistor (or use the
+    built-in LED on most Arduino boards)
 
   created  27 Sep 2005
   modified 30 Aug 2011

examples/03.Analog/AnalogInOutSerial/AnalogInOutSerial.ino

@@ -9,7 +9,7 @@
   - potentiometer connected to analog pin 0.
     Center pin of the potentiometer goes to the analog pin.
     side pins of the potentiometer go to +5V and ground
-  - LED connected from digital pin 9 to ground
+  - LED connected from digital pin 9 to ground through 220 ohm resistor
 
   created 29 Dec. 2008
   modified 9 Apr 2012

examples/03.Analog/AnalogInput/AnalogInput.ino

@@ -12,7 +12,7 @@
     one side pin (either one) to ground
     the other side pin to +5V
   - LED
-    anode (long leg) attached to digital output 13
+    anode (long leg) attached to digital output 13 through 220 ohm resistor
     cathode (short leg) attached to ground
 
   - Note: because most Arduinos have a built-in LED attached to pin 13 on the

examples/03.Analog/Calibration/Calibration.ino

@@ -12,7 +12,7 @@
 
   The circuit:
   - analog sensor (potentiometer will do) attached to analog input 0
-  - LED attached from digital pin 9 to ground
+  - LED attached from digital pin 9 to ground through 220 ohm resistor
 
   created 29 Oct 2008
   by David A Mellis

examples/03.Analog/Fading/Fading.ino

@@ -4,7 +4,7 @@
   This example shows how to fade an LED using the analogWrite() function.
 
   The circuit:
-  - LED attached from digital pin 9 to ground.
+  - LED attached from digital pin 9 to ground through 220 ohm resistor.
 
   created 1 Nov 2008
   by David A. Mellis

examples/04.Communication/Dimmer/Dimmer.ino

@@ -7,7 +7,7 @@
   set the brightness of the LED.
 
   The circuit:
-  - LED attached from digital pin 9 to ground.
+  - LED attached from digital pin 9 to ground through 220 ohm resistor.
   - Serial connection to Processing, Max/MSP, or another serial application
 
   created 2006

examples/04.Communication/PhysicalPixel/PhysicalPixel.ino

@@ -9,7 +9,7 @@
   Processing (see code below), Flash (via a serial-net proxy), PD, or Max/MSP.
 
   The circuit:
-  - LED connected from digital pin 13 to ground
+  - LED connected from digital pin 13 to ground through 220 ohm resistor
 
   created 2006
   by David A. Mellis

examples/04.Communication/ReadASCIIString/ReadASCIIString.ino

@@ -6,9 +6,9 @@
   It parses them into ints, and uses those to fade an RGB LED.
 
   Circuit: Common-Cathode RGB LED wired like so:
-  - red anode: digital pin 3
-  - green anode: digital pin 5
-  - blue anode: digital pin 6
+  - red anode: digital pin 3 through 220 ohm resistor
+  - green anode: digital pin 5 through 220 ohm resistor
+  - blue anode: digital pin 6 through 220 ohm resistor
   - cathode: GND
 
   created 13 Apr 2012