add to gitignore

.gitignore

@@ -13,3 +13,6 @@ auto/
 *.run.xml
 *.synctex.gz
 *.toc
+book.pdf
+book.fdb_latexmk
+book.fls

book.tex

@@ -15112,10 +15112,8 @@ def main() -> int :
   return 0
 \end{lstlisting}
 
-
 \fi
 
-
 \if\edition\racketEd
 \section{Reveal Functions and the $F_2$ language}
 \label{sec:reveal-functions-r5}