Add Changelog

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/ChangeLog.d/fix_zeroization.txt b/ChangeLog.d/fix_zeroization.txt
new file mode 100644
index 0000000..ad74d9c
--- /dev/null
+++ b/ChangeLog.d/fix_zeroization.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix possible crash in TLS PRF code, if a failure to allocate memory occurs.
+     Reported by Michael Madsen in #6516.