message: Update TFLite converter bug template to add a note about RNN conversion
diff: @@ -38,6 +38,9 @@ state what is wrong:
  - Producing correct results, but the model is slower than expected (model generated from old converter)
  +**RNN conversion support**
  +If converting TF RNN to TFLite fused RNN ops, please prefix [RNN] in the title.
  +
  **Any other info / logs**
  Include any logs or source code that would be helpful to diagnose the problem. If including tracebacks, please include the full traceback. Large logs and files should be attached.
  