step_kmeans: step_kmeans: a recipe step for clustering by kmeans.
In TatsumotoH/addstepr: add new step functions for recipes package (tidymodels)

step_kmeans: a recipe step for clustering by kmeans.

step_kmeans(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  skip = FALSE,
  num_k = NULL,
  retain = FALSE,
  id = rand_id("kmeans")
)

`role`	For model terms created by this step, what analysis role should they be assigned?
`trained`	A logical to indicate if the quantities for preprocessing have been estimated.
`skip`	A logical. Should the step be skipped when the recipe is baked by [recipes::bake.recipe()]?
`num_k`	The parameter num_k is passed to the parameter centers in kmeans function.
`retain`	A logical to specify whether the original predictors should be retained along with the new embedding variables.
`id`	A character string that is unique to this step to identify it.