edit opam file

opam

 opam-version: "1.2"
 name: "coq-stdpp"
 version: "dev"
-maintainer: "Robbert Krebbers"
-authors: "Robbert Krebbers"
+maintainer: "Ralf Jung <jung@mpi-sws.org>"
+authors: "Robbert Krebbers, Jacques-Henri Jourdan, Ralf Jung"
 bug-reports: "https://gitlab.mpi-sws.org/robbertkrebbers/coq-stdpp/issues"
 license: "BSD"
 dev-repo: "https://gitlab.mpi-sws.org/robbertkrebbers/coq-stdpp.git"