adding arduino examples for DHT11, blink, and temperature sensor

week3/examples/Projects/RP2040BlinkTest/src/main.cpp

@@ -0,0 +1,12 @@
+#include <Arduino.h>
+
+void setup() {
+  pinMode(LED_BUILTIN, OUTPUT); // GPIO 25
+}
+
+void loop() {
+  digitalWrite(LED_BUILTIN, HIGH);   // Turn LED on
+  delay(3000);                       // Wait 1 second
+  digitalWrite(LED_BUILTIN, LOW);    // Turn LED off
+  delay(1000);                       // Wait 1 second
+}