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

CODEOWNERS

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