[damned-lies] Add README instructions about testing

[Claude Paroz <claudep src gnome org>]

commit 38186581934c32b548c1eb9816629b8fc88009a6
Author: Claude Paroz <claude 2xlibre net>
Date:   Sat Aug 15 11:20:48 2015 +0200

    Add README instructions about testing
    
    Fixes bug #682681. Thanks Gil Forcada for the report and
    Grégoire Détrez for the initial patch.

 README |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)
---
diff --git a/README b/README
index 6db5b13..b837a51 100644
--- a/README
+++ b/README
@@ -81,6 +81,21 @@ Installation
 7 - Configure Sites in admin interface ('View on site' link, site address in
     sent mail).
 
+Running tests
+=============
+
+To run the tests, you need to install the mock package (in addition to the
+runtime dependencies):
+
+    pip install mock
+
+And then, run the tests with this command:
+
+    python manage.py test [optional path to run partial tests]
+
+Read https://docs.djangoproject.com/en/stable/topics/testing/ for more details
+about testing in Django projects.
+
 Maintenance tasks
 =================