message: cite the paper
diff: @@ -15,6 +15,9 @@ Included tools:
  * Translation validation plugins for clang and LLVM's `opt`
  * Standalone translation validation tool: `alive-tv` ([online](https://alive2.llvm.org))
  +For a technical introduction to Alive2, please see [our paper from
  +PLDI 2021](https://web.ist.utl.pt/nuno.lopes/pubs.php?id=alive2-pldi21).
  +
  WARNING
  -------
  