Added document explaining openSUSE installation

Added a new documentation page explaining how to install Docker on
openSUSE.

Docker-DCO-1.1-Signed-off-by: Flavio Castelli <fcastelli@suse.com> (github: flavio)

docs/sources/faq.rst

@@ -174,6 +174,7 @@ Linux:
 - Centos 6+
 - Gento
 - ArchLinux
+- openSUSE 12.3+
 
 Cloud:
 

docs/sources/installation/index.rst

@@ -22,6 +22,7 @@ Contents:
    fedora
    archlinux
    gentoolinux
+   openSUSE
    frugalware
    vagrant
    windows

docs/sources/installation/openSUSE.rst

@@ -0,0 +1,73 @@
+:title: Installation on openSUSE
+:description: Docker installation on openSUSE.
+:keywords: openSUSE, virtualbox, docker, documentation, installation
+
+.. _openSUSE:
+
+openSUSE
+========
+
+.. include:: install_header.inc
+
+.. include:: install_unofficial.inc
+
+Docker is available in **openSUSE 12.3 and later**. Please note that due to the
+current Docker limitations Docker is able to run only on the **64 bit**
+architecture.
+
+Installation
+------------
+
+The ``docker`` package from the `Virtualization project`_ on `OBS`_ provides
+Docker on openSUSE.
+
+
+To proceed with Docker installation please add the right Virtualization
+repository.
+
+.. code-block:: bash
+
+   # openSUSE 12.3
+   sudo zypper ar -f http://download.opensuse.org/repositories/Virtualization/openSUSE_12.3/ Virtualization
+
+   # openSUSE 13.1
+   sudo zypper ar -f http://download.opensuse.org/repositories/Virtualization/openSUSE_13.1/ Virtualization
+
+
+Install the Docker package.
+
+.. code-block:: bash
+
+   sudo zypper in docker
+
+It's also possible to install Docker using openSUSE's 1-click install. Just
+visit `this`_ page, select your openSUSE version and click on the installation
+link. This will add the right repository to your system and it will
+also install the `docker` package.
+
+Now that it's installed, let's start the Docker daemon.
+
+.. code-block:: bash
+
+    sudo systemctl start docker
+
+If we want Docker to start at boot, we should also:
+
+.. code-block:: bash
+
+   sudo systemctl enable docker
+
+The `docker` package creates a new group named `docker`. Users, other than
+`root` user, need to be part of this group in order to interact with the
+Docker daemon.
+
+.. code-block:: bash
+
+   sudo usermod -G docker <username>
+
+
+**Done!**, now continue with the :ref:`hello_world` example.
+
+.. _Virtualization project: https://build.opensuse.org/project/show/Virtualization
+.. _OBS: https://build.opensuse.org/
+.. _this: http://software.opensuse.org/package/docker