diff --git a/book b/book
deleted file mode 160000
index 6e3875eb62533de1f2c1088a477719eb57b9732c..0000000000000000000000000000000000000000
--- a/book
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 6e3875eb62533de1f2c1088a477719eb57b9732c