[tomboy] README: added a note about Tomboy-NG

[Alex Tereschenko <alexter src gnome org>]

commit e7a27fbe4589b7190f95bacb3b073ac2e17ff455
Author: Alex Tereschenko <frozen and blue gmail com>
Date:   Sat Jan 27 15:26:28 2018 +0100

    README: added a note about Tomboy-NG
    
    Signed-off-by: Alex Tereschenko <frozen and blue gmail com>

 README.md |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/README.md b/README.md
index 9f21014..6ca6907 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,9 @@ Copyright (C) 2004-2007 Alex Graveley <alex beatniksoftware com>
 
 Copyright (C) 2004-2017 Others
 
+**Please note that this repo is for the previous generation of Tomboy, which is no longer actively 
developed.**  
+**See [Tomboy-NG](https://github.com/tomboy-notes/tomboy-ng) for current activities.**
+
 The Tomboy homepage is located [here](https://wiki.gnome.org/Apps/Tomboy).
 
 We use GitHub to store sources and track bugs, see [Tomboy](https://github.com/tomboy-notes/tomboy).