Document installation using pip

Fixes #962
Signed-off-by: Michal Čihař <michal@cihar.com>

docs/admin/install.rst

@@ -208,6 +208,37 @@ On openSUSE or SLES you can install them using:
 
     zypper install libxslt-devel libxml2-devel freetype-devel python-devel
 
+.. _install-weblate:
+
+Installing Weblate
+------------------
+
+It is recommended to run latest version from Git. It is maintained stable and
+production ready.
+
+To get latest sources using Git use:
+
+.. code-block:: sh
+    
+    git clone https://github.com/nijel/weblate.git
+
+Alternatively you can use released archives. You can either download them from our 
+website <https://weblate.org/> or use pip installer.
+
+Installing Weblate by pip
++++++++++++++++++++++++++
+
+If you decode to install Weblate using pip installer, you will notice some
+differences. Most importantly the command line interface is installed  to the
+system path as :command:`weblate` instead of :command:`./manage.py` as used in
+this documentation. Also when invoking this command, you will have to specify
+settings, either by :envvar:`DJANGO_SETTINGS` or on the command line, for
+example:
+
+.. code-block:: sh
+
+    weblate --settings=yourproject.settings migrate
+
 .. _file-permissions:
 
 Filesystem permissions

docs/admin/quick.rst

@@ -13,7 +13,7 @@ Installing from sources
 #. Install all required dependencies, see :ref:`requirements`.
 
 #. Grab Weblate sources (either using Git or download a tarball) and unpack
-   them.
+   them, see :ref:`install-weblate`.
 
 #. Copy :file:`weblate/settings_example.py` to :file:`weblate/settings.py` and
    adjust it to match your setup. You will at least need to configure database