Add git ignore. First part of part 3 tut done.

digikey tutorials/part 3/and_gate.v

@@ -0,0 +1,15 @@
+// Modeule: when buttons 1 and 2 are pressed, turn on LED
+
+module and_gate (
+    // Inputs
+    input      pmod_0,
+    input      pmod_1,
+
+    // Outputs
+    output      led_0
+);
+
+    // Continuous assignment: not and and operators
+    assign led_0 = ~pmod_0 & ~pmod_1;
+
+endmodule