[PATCH 2 of 3] docs/installation: add section on installation from source

[Thomas De Schampheleire]

# HG changeset patch
# User Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>
# Date 1426366293 -3600
#      Sat Mar 14 21:51:33 2015 +0100
# Node ID f5e05f4a8bff420c63924b3764fcf33d162624ed
# Parent  42db321baa410e0cbf91003750fafeec0e9e5cbf
docs/installation: add section on installation from source

As we actually recommend this method, describe it as first option in the
installation instructions.

diff --git a/docs/installation.rst b/docs/installation.rst
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -10,6 +10,22 @@
 .. Note:: Alternative very detailed installation instructions for Ubuntu Server
    with celery, indexer and daemon scripts: https://gist.github.com/4546398
 
+Installing Kallithea from a source release
+------------------------------------------
+
+The Kallithea development repository is stable and can be used in production.
+Follow these instructions::
+
+        hg clone https://kallithea-scm.org/repos/kallithea
+        cd kallithea
+        virtualenv ../kallithea-venv
+        source ../kallithea-venv/bin/activate
+        python setup.py develop
+
+You can now proceed to :ref:`setup`.
+
+To upgrade, simply update the repository with ``hg pull -u`` and restart the
+server.
 
 Installing Kallithea from Python Package Index (PyPI)
 -----------------------------------------------------