Fixed version number typo.
diff --git a/src/main/docgen/book.xml b/src/main/docgen/book.xml
index 201eabf..b780c14 100644
--- a/src/main/docgen/book.xml
+++ b/src/main/docgen/book.xml
@@ -148,7 +148,7 @@
     since 2.3.24.</para>
 
     <simplesect>
-      <title>Latest stable release: 2.3.20</title>
+      <title>Latest stable release: 2.3.30</title>
 
       <para>Released on 2020-03-05. Requires J2SE 1.7 or higher.</para>