message: Document possible use of `runtime-macros`
  The `runtime-macros` crate provides all the functionality needed to get Tarpaulin working with procedural macros.
diff: @@ -194,6 +194,10 @@ pycobertura show --format html --output coverage.html cobertura.xml
  Then open `coverage.html` in your browser.
  +### Procedural Macros
  +
  +Normally, Tarpaulin can't report on code coverage within the code for a procedural macro. You'll need to add a test that expands the macro at run time in order to get those stats. The [`runtime-macros` crate](https://crates.io/crates/runtime-macros) was made for this purpose, and its documentation describes how to use it with Tarpaulin.
  +
  ## Issues and Contributing
  Issues, feature requests and pull requests are always welcome! For a guide on
  