Update CHANGELOG.md

Signed-off-by: Ricky Grassmuck <rigrassm@gmail.com>

CHANGELOG.md

@@ -25,6 +25,9 @@ Certbot adheres to [Semantic Versioning](https://semver.org/).
 * Adding a warning noting that future versions of Certbot will automatically configure the
   webserver so that all requests redirect to secure HTTPS access. You can control this
   behavior and disable this warning with the --redirect and --no-redirect flags.
+* Convert the tsig algorithm specified in the certbot_dns_rfc2136 configuration file to
+  all uppercase letters before validating. This makes the value in the config case
+  insensitive.
 
 ### Fixed