Update data-transform.qmd (hadley#1073)

A well written chapter. Just a very minor fix.

data-transform.qmd

@@ -65,7 +65,7 @@ But before we discuss their individual differences, it's worth stating what they
 
 3.  The result is always a new data frame.
 
-Because the first argument is a data frame and the output is a data frame, dplyr verbs work work well with the pipe, `|>`.
+Because the first argument is a data frame and the output is a data frame, dplyr verbs work well with the pipe, `|>`.
 The pipe takes the thing on its left and passes it along to the function on its right so that `x |> f(y)` is equivalent to `f(x, y)`, and `x |> f(y) |> g(z)` is equivalent to into `g(f(x, y), z)`.
 The easiest way to pronounce the pipe is "then".
 That makes it possible to get a sense of the following code even though you haven't yet learnt the details: