message: Fix formula and text rendering.
diff: @@ -40,15 +40,14 @@ class AdamOptimizer(optimizer_v2.OptimizerV2):
  Initialization:
  - $$m_0 := 0 (Initialize initial 1st moment vector)$$
  - $$v_0 := 0 (Initialize initial 2nd moment vector)$$
  - $$t := 0 (Initialize timestep)$$
  -
  + $$m_0 := 0 \text{(Initialize initial 1st moment vector)}$$
  + $$v_0 := 0 \text{(Initialize initial 2nd moment vector)}$$
  + $$t := 0 \text{(Initialize timestep)}$$
  The update rule for `variable` with gradient `g` uses an optimization
  described at the end of section2 of the paper:
  $$t := t + 1$$
  - $$lr_t := \text{learning_rate} * \sqrt{(1 - beta_2^t) / (1 - beta_1^t)}$$
  + $$lr_t := \text{learning\_rate} * \sqrt{1 - beta_2^t} / (1 - beta_1^t)$$
  $$m_t := beta_1 * m_{t-1} + (1 - beta_1) * g$$
  $$v_t := beta_2 * v_{t-1} + (1 - beta_2) * g * g$$
  