Chapter13 (#13)

* start chapter 13

* First draft chapter notes

* Include data as parquet

* Fix typos

* add libraries

* tidy description

Author: DrEntropy

.gitignore

@@ -10,3 +10,4 @@ bookclub-r_baseball.knit.md
 bookclub-r_baseball_files
 libs
 *.html
+data_large