call-related changes

Author: topepo

NEWS.md

@@ -14,6 +14,10 @@
 
  * A new main argument was added to `boost_tree()` called `stop_iter` for early stopping. The `xgb_train()` function gained arguments for early stopping and a percentage of data to leave out for a validation set. 
 
+ * If `fit()` is used and the underlying model uses a formula, the _actual_ formula is pass to the model (instead of a placeholder). This makes the model call better. 
+ 
+ * A function named `repair_call()` was added. This can help change the underlying models `call` object to better reflect what they would have obtained if the model function had been used directly (instead of via `parsnip`). This is only useful when the user chooses a formula interface and the model uses a formula interface. It will also be of limited use when a recipes is used to construct the feature set in `workflows` or `tune`. 
+ 
 # parsnip 0.1.1
 
 ## New Features