Remove duplicated return values from docs (#3850)

R-package/R/lgb.Dataset.R

@@ -970,7 +970,6 @@ slice <- function(dataset, ...) {
 }
 
 #' @rdname slice
-#' @return constructed sub dataset
 #' @export
 slice.lgb.Dataset <- function(dataset, idxset, ...) {
 

R-package/man/slice.Rd

@@ -17,8 +17,6 @@ slice(dataset, ...)
 \item{idxset}{an integer vector of indices of rows needed}
 }
 \value{
-constructed sub dataset
-
 constructed sub dataset
 }
 \description{