Changelog entry for the ARIA_ALT and CAMELLIA_ALT fixes

Fix ARMmbed/mbed-os#14694

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

ChangeLog.d/aria-alt.txt

@@ -0,0 +1,5 @@
+Bugfix
+   * Fix some issues affecting MBEDTLS_ARIA_ALT implementations: a misplaced
+     directive in a header and a missing initialization in the self-test.
+   * Fix a missing initialization in the Camellia self-test, affecting
+     MBEDTLS_CAMELLIA_ALT implementations.