Couple of changes: (#8)

* Update to 3.9.0 roslyn.
* Add the necessary usings to make the hello world example compile as a top-level program (with the right package references, of course).

Author: 333fred

Basic.Reference.Assemblies.UnitTests/Basic.Reference.Assemblies.UnitTests.csproj

@@ -10,7 +10,7 @@
     <PackageReference Include="xunit" Version="2.4.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.0" />
     <PackageReference Include="coverlet.collector" Version="1.2.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.9.0" />
   </ItemGroup>
 
   <ItemGroup>

Directory.Build.targets

@@ -5,6 +5,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis" Version="3.8.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis" Version="3.9.0" />
   </ItemGroup>
-</Project>
+</Project>

README.md

@@ -16,6 +16,10 @@ for `netstandard2.0`, `netcoreapp3.1` and `net5.0`. These can be easily
 integrated into the existing Roslyn APIs.
 
 ```c#
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Basic.Reference.Assemblies;
+
 var code = @"
 using System;
 static class Program