message: Fix unwanted typo caused protobuf load failure
diff: @@ -80,4 +80,5 @@ $$lr_t := \text{learning_rate} * \sqrt{(1 - beta_2^t) / (1 - beta_1^t)}$$
  $$m_t := beta_1 * m_{t-1} + (1 - beta_1) * g$$
  $$v_t := beta_2 * v_{t-1} + (1 - beta_2) * g * g$$
  $$variable := variable - lr_t * m_t / (\sqrt{v_t} + \epsilon)$$
  +END
  }
  