Added shape docs for LeakyReLU layer from Keras (#211)

https://keras.io/api/layers/activation_layers/leaky_relu/

tensorflow/src/main/kotlin/org/jetbrains/kotlinx/dl/api/core/layer/activation/LeakyReLU.kt

@@ -16,6 +16,12 @@ import org.tensorflow.op.Ops
  * f(x) = x,                if x >= 0
  * f(x) = alpha * x         if x < 0
  * ```
+ *
+ * __Input shape:__  Arbitrary. Use the keyword argument `input_shape`
+ *                   (tuple of integers, does not include the batch axis)
+ *                   when using this layer as the first layer in a model.
+ * __Output shape:__ 2D tensor with shape `(batch_size, channels)`.
+ *
  * @property [alpha] Negative slope coefficient. Should be >= 0.
  * @constructor Creates [LeakyReLU] object.
  * @since 0.3