Add missing asterisk to doxygen closures

Clarify section names next to closing braces
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index 3c11a99..e157efa 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -955,8 +955,8 @@
 #endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-/* \} name */
-/* \} addtogroup x509_module */
+/** \} name Structures and functions for parsing and writing X.509 certificates */
+/** \} addtogroup x509_module */
 
 #if defined(MBEDTLS_X509_CRT_WRITE_C)
 /**