message: docs: fix a grammar mistake
  Grammar mistake is in the JsonPipe section
  PR Close
diff: @@ -548,7 +548,7 @@ It displays the same hero data in JSON format by chaining through to the built-i
  The [JsonPipe](api/common/JsonPipe)
  -provides an easy way to diagnosis a mysteriously failing data binding or
  +provides an easy way to diagnose a mysteriously failing data binding or
  inspect an object for future binding.
  