Recommend latest version of Microsoft.XmlSerializer.Generator

[KSchlobohm]

Update samples to use latest NuGet package reference and to include a notation that the latest version is always recommended.

Would also be helpful to include a subsection that describes how to use Xml Serializer Generator in projects that are multi-targeting net48 and net5.0 on projects that are in a hybrid state while migrating.

I believe this can be accomplished using a csproj similar to:

<PropertyGroup Condition=" '$(TargetFramework)' == 'net48'">
    <GenerateSerializationAssemblies>On</GenerateSerializationAssemblies>
    <SGenUseProxyTypes>false</SGenUseProxyTypes>
  </PropertyGroup>
  <PropertyGroup Condition="'$(TargetFramework)' != 'net48' ">
    <_XmlSerializerGeneratorVersion>5.0.0</_XmlSerializerGeneratorVersion>
  </PropertyGroup>
  <ItemGroup Condition="'$(TargetFramework)' != 'net48' ">
    <PackageReference Include="Microsoft.XmlSerializer.Generator" Version="$(_XmlSerializerGeneratorVersion)" />
    <DotNetCliToolReference Include="Microsoft.XmlSerializer.Generator" Version="$(_XmlSerializerGeneratorVersion)" />
  </ItemGroup>

Addressing the multi-target scenario could help to explain how to resolve build errors that look like the following:

17>------ Build started: Project: ExampleProject, Configuration: Release Any CPU ------
17>SGEN : error : An attempt was made to load an assembly with an incorrect format: C:\dev\.nuget\packages\system.memory\4.5.1\ref\netstandard2.0\System.Memory.dll.
17>Done building project "ExampleProject.csproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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Document Details

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• ID: cb8026b7-96b0-eab2-e6ec-93d9c61e95e6
• Version Independent ID: 1ed6e1bf-7228-608d-b3fa-fa517e55386e
• Content: Microsoft XML Serializer Generator - .NET
• Content Source: docs/core/additional-tools/xml-serializer-generator.md
• Product: dotnet-fundamentals
• GitHub Login: @HongGit
• Microsoft Alias: dotnetcontent

[KalleOlaviNiemitalo]

The "An attempt was made to load an assembly with an incorrect format" error, caused by the .NET Framework SGEN trying to load a reference assembly, can also occur when targeting .NET Framework and referencing a NuGet package that includes a reference assembly. This has been discussed in dotnet/msbuild#2707, dotnet/wcf#3991, and dotnet/sdk#1630. I don't think the article should recommend adding conditions that check $(TargetFramework). Rather, it should recommend using the Microsoft.XmlSerializer.Generator package on all target frameworks.

#28844 added documentation for SGenReferences and other properties. However, the article currently recommends Microsoft.XmlSerializer.Generator 1.0.0, which ignores all of those properties. Microsoft.XmlSerializer.Generator 2.1.0-preview4.19212.13 is the first version that supports those properties. The article should be changed to recommend Microsoft.XmlSerializer.Generator 2.1.0 or a higher version, or to describe which versions support the properties.