The cookbook doesn't document how to do local development and referencing of source generators in a single project. Think we should add that in as it's a typical case, particularly now that we support debugging such scenarios as of VS 16.10.

<ProjectReference 
  Include="..\SourceGeneratorSamples\SourceGeneratorSamples.csproj"
  OutputItemType="Analyzer"
  ReferenceOutputAssembly="false" />