fix build

Author: wiz0u

book.toml

@@ -1,13 +1,13 @@
 [book]
 authors = ["Poulad Ashrafpour", "Aleksey Usatov", "Wizou", "karb0f0s", "Miha Zupan"]
-multilingual = false
 src = "src"
 title = "A guide to Telegram.Bot library"
 site-url = "https://telegrambots.github.io/book/"
 language = "en"
 
 [output.html]
 git-repository-url = "https://github.com/TelegramBots/book"
+site-url = "/book/"
 additional-css = ["theme/custom.css"]
 
 [output.html.fold]