add Programmyday form github

DoppelteBuchstaben/Program.cs

@@ -0,0 +1,13 @@
+namespace DoppelteBuchstaben
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            DuplicateChars duplicate = new DuplicateChars();
+            string text = Console.ReadLine();
+            Console.WriteLine(duplicate.ContainsDuplicateChars(text));
+            Console.WriteLine(duplicate.RemoveDuplicateChars(text));
+        }
+    }
+}