Resolve "Prepare for release v0.16.0"

Closes #322 (closed)

❗ README.md has not been updated since last release. Please check if it needs updating.

• Check that project version(s) match the release version
• Check changelog issues are correctly categorized
• Add release summary to the changelog if one was not automatically generated
• Update README with any changes since last release
• Update readme with new link to SCL playground and website, nuget guide
• Remove any .config folders
• csproj changes
  • Update PackageProjectUrl to sequence.sh
  • Ensure RepositoryUrl is a .git address
  • Add PackageReadmeFile property
  • Add source link configuration (deterministic build, symbols, source link, package files)
  • Add Microsoft.SourceLink.GitLab package
• Add PUBLISH_NUGETORG flag to the CI files