message: Fixed text in internals doc that implied structs can be root
diff: @@ -62,7 +62,7 @@ when needed. Unsigned means they can only point in one direction, which
  typically is forward (towards a higher memory location). Any backwards
  offsets will be explicitly marked as such.
  -The format starts with an `uoffset_t` to the root object in the buffer.
  +The format starts with an `uoffset_t` to the root table in the buffer.
  We have two kinds of objects, structs and tables.
  