Include brief description from Readme into documentation.
Rational: When going to http://relatorio.readthedocs.org/ there currently is no explanation what relatorio is.
- Remove pointer to documentation from Readme.
- Rename Readme to Readme.rst to match other Tryton projects.
- Include Readme.rst in doc/index.rst
Moving the description to doc/index.rst and adding a symlink did not work since the index.rst contains a toctree
which twine wouls report as an error.
Edited by Hartmut Goebel