Update Changelog.txt

(Fixes issue #1579)

This was fixed in commit cbaccac8b29a0bf7c4ef158921e407bb74e1eb51 which is included in release 1.8.7

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Correctly show balloon title and icon

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>