[add] README content

README.md

+# java-service-datamatrix
+
+## Description
+
+Java service to encode an decode datamatrix codes.
+
+## License
+
+[![License: CC0-1.0](https://licensebuttons.net/l/zero/1.0/80x15.png)](http://creativecommons.org/publicdomain/zero/1.0/)