Fix typo in xsv cat -h

src/cmd/cat.rs

@@ -8,8 +8,8 @@ static USAGE: &'static str = "
 Concatenates CSV data by column or by row.
 
 When concatenating by column, the columns will be written in the same order as
-the inputs given. The number of rows in the result is always equivalent to to
-the minimum number of rows across all given CSV data. (This behavior can be
+the inputs given. The number of rows in the result is always equivalent to the
+minimum number of rows across all given CSV data. (This behavior can be
 reversed with the '--pad' flag.)
 
 When concatenating by row, all CSV data must have the same number of columns.