italicize book title (#607)

Author: wibeasley

README.Rmd

@@ -65,7 +65,7 @@ local({
 The duckplyr package will run all of your existing dplyr code with identical results, using [DuckDB](https://duckdb.org/) where possible to compute the results faster.
 In addition, you can analyze larger-than-memory datasets straight from files on your disk or from the web.
 
-If you are new to dplyr, the best place to start is the [data transformation chapter](https://r4ds.hadley.nz/data-transform) in R for Data Science.
+If you are new to dplyr, the best place to start is the [data transformation chapter](https://r4ds.hadley.nz/data-transform) in _R for Data Science_.
 
 
 ## Installation