Update i2c.md

Builtin LED is not set as output in Reader (I2C slave) program. Thus the LED is not turning on.
So following line needs to be added.
  pinMode(LED_BUILTIN,OUTPUT);  // sets onBoard LED as output

Author: nikhilsigma

content/hardware/03.nano/boards/nano-every/tutorials/I2C/i2c.md

@@ -91,6 +91,7 @@ Let's start by adding the `Wire.h` library by adding the `#include <Wire.h>` sta
 void setup() {
   Wire.begin(8);                // join i2c bus with address #8
   Wire.onReceive(receiveEvent); // function that executes whenever data is received from writer
+  pinMode(LED_BUILTIN,OUTPUT);  // sets onBoard LED as output
 }
 ```
 
@@ -186,6 +187,7 @@ If you choose to skip the code building section, the complete code for both the
 void setup() {
   Wire.begin(8);                // join i2c bus with address #8
   Wire.onReceive(receiveEvent); // function that executes whenever data is received from writer
+  pinMode(LED_BUILTIN,OUTPUT);  // sets onBoard LED as output
 }
 
 void loop() {