Minor reword

Author: rachlobay

R/methods-epi_df.R

@@ -79,7 +79,7 @@ summary.epi_df = function(object, ...) {
 
   cn <- names(res)
 
-  # Duplicate key columns, Abort
+  # Duplicate columns, Abort
   dup_col_names = cn[duplicated(cn)]
   if (length(dup_col_names) != 0) {
     Abort(paste0("Column name(s) ",