message: update docs - structs can't be roots
diff: @@ -239,9 +239,9 @@ included files (those you still generate separately).
  ### Root type
  -This declares what you consider to be the root table (or struct) of the
  -serialized data. This is particularly important for parsing JSON data,
  -which doesn't include object type information.
  +This declares what you consider to be the root table of the serialized
  +data. This is particularly important for parsing JSON data, which doesn't
  +include object type information.
  ### File identification and extension
  