Added new Utilities documentation to manifest

When adding the `Utilities` schema documentation (#67296a8), I neglected to remember that the database project doesn't use the new Visual Studio 2017+ project format and, therefore, requires _explicitly_ including files in the manifest. Oops.

Author: JeremyCaney

OnTopic.Data.Sql.Database/OnTopic.Data.Sql.Database.sqlproj

@@ -118,6 +118,7 @@
   </ItemGroup>
   <ItemGroup>
     <None Include="README.md" />
+    <None Include="Utilities\README.md" />
   </ItemGroup>
   <ItemGroup>
     <RefactorLog Include="OnTopic.Data.Sql.Database.refactorlog" />