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Fix contents of the README, point to the SUSE docs and
fix symlinks and other information

README.rst

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+Distribution Migration System
+=============================
+
+.. |GitHub Action Unit Types| image:: https://github.com/SUSE/suse-migration-services/actions/workflows/ci-testing.yml/badge.svg
+   :target: https://github.com/SUSE/suse-migration-services/actions
+.. |Doc| replace:: `Documentation <https://documentation.suse.com/suse-distribution-migration-system/15/html/distribution-migration-system/index.html>`__
+
+|GitHub Action Unit Types|
+
+**Migrate from one major SUSE version to another with the DMS**
+
+Contents
+--------
+
+  * |Doc|
+  * Contributing
+
+.. _contributing:
+
+Contributing
+============
+
+The Python project uses `tox` to setup a development environment
+for the desired Python version.
+
+The following procedure describes how to create such an environment:
+
+1.  Let tox create the virtual environment(s):
+
+    .. code:: bash
+
+       $ tox
+
+2.  Activate the virtual environment
+
+    .. code:: bash
+
+       $ source .tox/3/bin/activate
+
+3.  Install requirements inside the virtual environment:
+
+    .. code:: bash
+
+       $ pip install -U pip setuptools
+       $ pip install -r .virtualenv.dev-requirements.txt
+
+4.  Let setuptools create/update your entrypoints
+
+    .. code:: bash
+
+       $ ./setup.py develop
+
+Once the development environment is activated and initialized with
+the project required Python modules, you are ready to work.
+
+In order to leave the development mode just call:
+
+.. code:: bash
+
+   $ deactivate
+
+To resume your work, change into your local Git repository and
+run `source .tox/3/bin/activate` again. Skip step 3 and 4 as
+the requirements are already installed.