NEWS: prepare for v2.6.0 release

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Jakub Jelen <jjelen@redhat.com>

NEWS

+v2.6.0
+======
+
+- provides implementation of GSC-IS 2.1 (aka CAC version 2) to improve
+  interoperatibility with guest software using the emulated or shared
+  smart cards. The previously implemented CACv1 specification is no
+  longer supported by any other application so the old code is gone
+  and any application depending on this old standard will not work
+  anymore.
+- vscclient is no longer installed, as it is not an end-user support
+  solution
+- various bug & leak fixes
+
 v2.5.3
 ======