[tepl] readme: add section 'How to contribute'

[Sébastien Wilmet <swilmet src gnome org>]

commit a790eed77ae2b4b700175278b65396e5508bb028
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Thu Jun 15 15:14:34 2017 +0200

    readme: add section 'How to contribute'

 README |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/README b/README
index 0119e5d..beea4e1 100644
--- a/README
+++ b/README
@@ -49,3 +49,8 @@ To build the latest version of Tepl plus its dependencies from Git, Jhbuild is
 recommended:
 
     https://wiki.gnome.org/Projects/Jhbuild
+
+How to contribute
+-----------------
+
+See the file 'HACKING'.