message: Add an explanation about using FlatbufferModel::GetMinimumRuntime().
diff: @@ -139,6 +139,10 @@ class FlatBufferModel {
  // version encodes the minimum required interpreter version to run the
  // flatbuffer model. If the minimum version can't be determined, an empty
  // string will be returned.
  + // Note that the returned minimum version is a lower-bound but not a strict
  + // lower-bound; ops in the graph may not have an associated runtime version,
  + // in which case the actual required runtime might be greater than the
  + // reported minimum.
  string GetMinimumRuntime() const;
  /// Returns true if the model identifier is correct (otherwise false and
  