Running the --format github formatter outputs warning/error messages like these:

::error file=app/lib/register/creates_user.rb,line=9,col=33::Lint/InterpolationCheck: Interpolation in single quoted string detected. Use double quoted strings if you need interpolation.

But these aren't resulting in the pretty inline annotations highlighted in the README's screenshots. Instead they just show up at the bottom of the build summary (and don't link directly to the code):