Add hello world csharp example

Plugins/HelloWorldCSharp/Main.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Wox.Plugin;
+
+namespace HelloWorldCSharp
+{
+    class Main : IPlugin
+    {
+        public List<Result> Query(Query query)
+        {
+            var result = new Result
+            {
+                Title = "Hello Word from CSharp",
+                SubTitle = $"Query: {query.Search}",
+                IcoPath = "app.png"
+            };
+            return new List<Result> {result};
+        }
+
+        public void Init(PluginInitContext context)
+        {
+            
+        }
+    }
+}