Add ChangeLog entry for PR #1567.

ChangeLog entry for platform support for the Haiku OS. PR #1567.
diff --git a/ChangeLog b/ChangeLog
index a1d7c8b..9195fac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,8 @@
    * Add new crypto primitives from RFC 7539: stream cipher Chacha20, one-time
      authenticator Poly1305 and AEAD construct Chacha20-Poly1305. Contributed by
      Daniel King (#485).
+   * Add platform support for the Haiku OS. (https://www.haiku-os.org).
+     Contributed by Augustin Cavalier.
 
 Bugfix
    * Fix the key_app_writer example which was writing a leading zero byte which