[tomboy] NEWS: update for 1.15.9 release

[Alex Tereschenko <alexter src gnome org>]

commit c22bfefd5855634bdba7b40b3d97aaa0965c6997
Author: Alex Tereschenko <frozen and blue gmail com>
Date:   Sun Jul 16 13:55:07 2017 +0200

    NEWS: update for 1.15.9 release
    
    Signed-off-by: Alex Tereschenko <frozen and blue gmail com>

 NEWS |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index be05a41..7f2c5db 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,11 @@ Please send questions and suggestions to
 Please report bugs using GitHub
 (https://github.com/tomboy-notes/tomboy/issues).
 
+Version 1.15.9
+* Fixed search and highlight problems for notes with multibyte characters (gh45)
+* Fixed Tomboy crash upon deleting a note after closing Search All window (gh52)
+* Main README updated & converted to Markdown (thanks DamienDoumer for initial idea!)
+
 Version 1.15.8
 * Translation updates: da, pt_BR, cs, pl, sr, sv, hu, de, id, lt
 * Removed confusing Esc key binding to the default button in dialogs (gh22)