diff --git a/book.json b/book.json
index d085572..61556a3 100644
--- a/book.json
+++ b/book.json
@@ -1,5 +1,5 @@
 {
-    "plugins": [ "github"
+    "plugins": [ "github",
      "toggle-chapters"],
     "pluginsConfig": {
         "github": {