Edits to README for clarity

Author: juliasilge

NEWS.md

@@ -13,7 +13,7 @@
 
 * The xgboost engine for boosted trees was translating `mtry` to xgboost's `colsample_bytree`. We now map `mtry` to `colsample_bynode` since that is more consistent with how random forest works. `colsample_bytree` can still be optimized by passing it in as an engine argument. `colsample_bynode` was added to xgboost after the `parsnip` package code was written. (#495)
 
-* For xgboost boosting, `mtry` and `colsample_bytree` can be passed as integer counts or proportions while `subsample` and `validation` should be proportions. `xgb_train()` now has a new option `counts` for state what scale `mtry` and `colsample_bytree` are being used. (#461)  
+* For xgboost, `mtry` and `colsample_bytree` can be passed as integer counts or proportions, while `subsample` and `validation` should always be proportions. `xgb_train()` now has a new option `counts` (`TRUE` or `FALSE`) that states which scale for `mtry` and `colsample_bytree` is being used. (#461)  
 
 ## Other Changes