build: correct links in the OPAM file

Author: favonia

mugen.opam

@@ -7,9 +7,9 @@ This package implements the generalization of Conor McBride’s crude but effect
 maintainer: "favonia <favonia@gmail.com>"
 authors: "The RedPRL Development Team"
 license: "Apache-2.0"
-homepage: "https://github.com/RedPRL/makubex"
-bug-reports: "https://github.com/RedPRL/makubex/issues"
-dev-repo: "git+https://github.com/RedPRL/makubex.git"
+homepage: "https://github.com/RedPRL/mugen"
+bug-reports: "https://github.com/RedPRL/mugen/issues"
+dev-repo: "git+https://github.com/RedPRL/mugen.git"
 depends: [
   "dune" {>= "2.0"}
   "ocaml" {>= "4.13"}