message: Update distribution strategy readme to reflect metrics support during training.
diff: @@ -116,8 +116,6 @@ in the input function gives a solid boost in performance. When using
  ## Caveats
  This feature is in early stages and there are a lot of improvements forthcoming:
  -* Metrics are not yet supported during distributed training. They are still
  -supported during the evaluation.
  * Summaries are only computed in the first tower in `MirroredStrategy`.
  * Evaluation is not yet distributed.
  * Eager support is in the works; performance can be more challenging with eager
  