message: Fix typo in FileWriter docs.
diff: @@ -325,7 +325,7 @@ class FileWriter(SummaryToEventTransformer):
  ```
  The `session` argument to the constructor makes the returned `FileWriter` a
  - a compatibility layer over new graph-based summaries (`tf.contrib.summary`).
  + compatibility layer over new graph-based summaries (`tf.contrib.summary`).
  Crucially, this means the underlying writer resource and events file will
  be shared with any other `FileWriter` using the same `session` and `logdir`,
  and with any `tf.contrib.summary.SummaryWriter` in this session using the
  