[libsigcplusplus] NEWS: Mention the move to github.

[Murray Cumming <murrayc src gnome org>]

commit cb0c10dba992042c2b072a934f9b9e060346c86f
Author: Murray Cumming <murrayc murrayc com>
Date:   Sat Mar 10 15:24:22 2018 +0100

    NEWS: Mention the move to github.
    
    For now, we will still release tarballs to GNOME's servers,
    and use the GNOME mailing list.

 NEWS |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index 8c44af8..dcbece9 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,8 @@
+libsigc++ has now moved to
+https://github.com/libsigcplusplus/libsigcplusplus
+This git repository at git.gnome.org/browse/libsigcplusplus
+will not be updated.
+
 2.99.10: (unstable)
 
 * slot_base::set_parent(): Create a dummy slot_rep if necessary