message: Add clarifying comment on FromHostLiteral API.
diff: @@ -329,6 +329,9 @@ class PyLocalBuffer {
  std::shared_ptr<void> buffer_reference, PyLocalClient* client,
  Device* device);
  + // Note that literal must remain in scope until the transfer has completed, so
  + // the caller should, for example, wait for BlockHostUntilReady() completes on
  + // the return value before letting literal go out of scope.
  static StatusOr<std::unique_ptr<PyLocalBuffer>> FromHostLiteral(
  const LiteralSlice& literal, PyLocalClient* client, Device* device);
  