added dotnet sample

dotnet-sample/dotnet-sample.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <RootNamespace>dotnet_sample</RootNamespace>
+  </PropertyGroup>
+
+</Project>