added codeowners file as part of Issue UNICADO/Unicado-Package #6

CODEOWNERS

+# Repository-specific code ownership
+*                           @unicado-consortium/rwth    @unicado-consortium/tub-lb
+
+# File-specific code ownership
+.gitattributes                @Florian.Schueltke
+.gitignore                    @Florian.Schueltke
+CODEOWNERS                    @Florian.Schueltke
+LICENSE                       @Florian.Schueltke
+README.md                     @Florian.Schueltke