updating documentation

README.rst

@@ -66,6 +66,18 @@ You must then set the crawler to be run once every few minutes with a limited nu
 
     */2 * * * * cd {root};source venv/bin/activate;./manager.py fetch --limit 20 -r
 
+Upgrading
+---------
+
+The ``master`` branch should always be working and it is recommended you install the project using this one. Partial or unstable change maybe present in the ``develop`` branch even if it'll be avoided as much as we can.
+So if you're planning on using the project from the source, you should be using the ``master`` branch only, but, if you're proposing patches, please make your pull request against the ``develop`` branch.
+
+If you have already installed JARR and want to upgrade to a later version, you may encounter some problem if some change have appeared in the model. To fix this, upgrade your database with the following commaned :
+
+.. code:: bash
+
+    ./manager.py db upgrade
+
 License
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