Update mkocaml.opam

Author: chrisnevers

mkocaml.opam

@@ -7,6 +7,7 @@ homepage: "https://github.com/chrisnevers/mkocaml"
 bug-reports: "https://github.com/chrisnevers/mkocaml/issues"
 dev-repo: "git://github.com/chrisnevers/mkocaml.git"
 synopsis: "Tool to generate OCaml projects"
+license: "BSD-3"
 build: [
   ["dune" "subst"] {pinned}
   ["dune" "build" "-p" name "-j" jobs]