Drop multilingual field from the book config
diff --git a/docs/book/book.toml b/docs/book/book.toml
index edf11fa..c77eabd 100644
--- a/docs/book/book.toml
+++ b/docs/book/book.toml
@@ -1,7 +1,6 @@
 [book]
 authors = ["The rust-analyzer authors"]
 language = "en"
-multilingual = false
 src = "src"
 title = "rust-analyzer"