Add README with copyright

README.md

+# PARTONS/NumA++
+
+## Documentation
+
+See [partons.cea.fr](http://partons.cea.fr).
+
+## Release
+
+To checkout the released version, use the tag `v1.0` (or subsequent versions) of the branch `release-v1`.
+
+## Licensing
+
+Copyright (C) 2018  PARTONS team.
+
+Under GPLv3. See [LICENSE](LICENSE) file.
+
+## Contact
+
+See [contact page](http://partons.cea.fr/partons/doc/html/contact.html).
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