Update CONTRIBUTING.md

point to IQSS repo

Author: qqmyers

CONTRIBUTING.md

@@ -2,6 +2,8 @@
 
 Thank you for your interest in contributing to Dataverse! We are open to contributions from everyone.
 
+Please make contributions to the main repository: https://github.com/IQSS/dataverse 
+
 Please see our [Contributor Guide][] for how you can help!
 
 [Contributor Guide]: https://guides.dataverse.org/en/latest/contributor/index.html