[atk] NEWS file: added 2.15.91 entry

[Alejandro Piñeiro Iglesias <apinheiro src gnome org>]

commit c29153f70bdbb34194f3f8ca015c1199a9d4c1b7
Author: Alejandro Piñeiro <apinheiro igalia com>
Date:   Tue Mar 3 18:09:39 2015 +0100

    NEWS file: added 2.15.91 entry
    
    Accidentally not included on last release commit.

 NEWS |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index 5faf399..c17fa30 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,17 @@
+Changes in version 2.15.91:
+===========================
+*
+* Building:
+   * Bug 744413: Stop using deprecated GNOME-specific autoconf macros
+     on configure.ac
+   * Stop using deprecated gnome-autogen.sh on autogen.sh
+
+Contributors:
+Javier Jardón
+
+Translations:
+Muhammet Kara (tr), Dušan Kazik (sk)
+
 Changes in version 2.15.4:
 ==========================
 *