Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -9,8 +9,8 @@ tab).
 
 If you want to report a bug, please use the
 [issue tracker](https://gitlab.mpi-sws.org/FP/iris-coq/issues), which also
-requires a GitLab account.  To contribute code, please send your MPI-SWS GitLab
-username to [Ralf Jung](https://gitlab.mpi-sws.org/jung) to enable personal
-projects for your account.  Then you can fork the
+requires an MPI-SWS GitLab account.  To contribute code, please send your
+MPI-SWS GitLab username to [Ralf Jung](https://gitlab.mpi-sws.org/jung) to
+enable personal projects for your account.  Then you can fork the
 [Iris git repository](https://gitlab.mpi-sws.org/FP/iris-coq/), make your
 changes in your fork, and create a merge request.