Tidy-up remaining TODOs

[mrlacey]

for tracking

The following TODOs exist in the codebase and need addressing:

• Directory.Build.targets: Include these in the shared space
• ReadMe.md Add info about copying template. - Addressed by add link to details about creating a new experiment #112
• build.yml Detect experiments | Detect experiments - Addressed by Pack all experiments individually #106
• ToolkitSampleMetadataGenerator.Documentation.cs
  • Figure out line location
  • Should generate the enum from these or something?
  • extract index to get proper line number?
  • extract index to get proper line number?
  • Emit a better error that no documentation is here?
  • Add list of sample ids in document
• ToolkitSampleMetadataGenerator.Sample.cs Emit a better error that no samples are here?
• ToolkitSampleMetadataTests.cs We should have this return the references to the registries or something so we can check the generated output?
• ToolkitDocumentationRenderer.xaml Display Header for name of sample?