Bump version to 3.2.1

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index 282e9bf..c05042b 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -22,7 +22,7 @@
  */
 
 /**
- * @mainpage mbed TLS v3.2.0 source code documentation
+ * @mainpage mbed TLS v3.2.1 source code documentation
  *
  * This documentation describes the internal structure of mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in