message: Fix docstring format for activation layers.
  Split most of the math formula into separate lines.
diff: @@ -34,8 +34,11 @@ class LeakyReLU(Layer):
  """Leaky version of a Rectified Linear Unit.
  It allows a small gradient when the unit is not active:
  - $$f(x) = alpha * x if x < 0$$
  - $$f(x) = x if x >= 0$$
  +
  + ```
  + f(x) = alpha * x if x < 0
  + f(x) = x if x >= 0
  + ```
  Usage:
  @@ -84,8 +87,12 @@ class PReLU(Layer):
  """Parametric Rectified Linear Unit.
  It follows:
  - `f(x) = alpha * x for x < 0`,
  - `f(x) = x for x >= 0`,
  +
  + ```
  + f(x) = alpha * x for x < 0
  + f(x) = x for x >= 0
  + ```
  +
  where `alpha` is a learned array with the same shape as x.
  Input shape:
  @@ -174,8 +181,11 @@ class ELU(Layer):
  """Exponential Linear Unit.
  It follows:
  - `f(x) = alpha * (exp(x) - 1.) for x < 0`,
  - `f(x) = x for x >= 0`.
  +
  + ```
  + f(x) = alpha * (exp(x) - 1.) for x < 0
  + f(x) = x for x >= 0
  + ```
  Input shape:
  Arbitrary. Use the keyword argument `input_shape`
  @@ -212,8 +222,11 @@ class ThresholdedReLU(Layer):
  """Thresholded Rectified Linear Unit.
  It follows:
  - `f(x) = x for x > theta`,
  - `f(x) = 0 otherwise`.
  +
  + ```
  + f(x) = x for x > theta
  + f(x) = 0 otherwise`
  + ```
  Input shape:
  Arbitrary. Use the keyword argument `input_shape`
  @@ -287,9 +300,12 @@ class ReLU(Layer):
  With default values, it returns element-wise `max(x, 0)`.
  Otherwise, it follows:
  - $$f(x) = max_value if x >= max_value$$
  - $$f(x) = x if threshold <= x < max_value$$
  - $$f(x) = negative_slope * (x - threshold) otherwise$$
  +
  + ```
  + f(x) = max_value if x >= max_value
  + f(x) = x if threshold <= x < max_value
  + f(x) = negative_slope * (x - threshold) otherwise
  + ```
  Usage:
  