message: Change `vcpkg build_external` to `vcpkg build-external`
diff: @@ -11,7 +11,7 @@ namespace vcpkg::Commands
  {"remove", &Remove::perform_and_exit},
  {"build", &Build::perform_and_exit},
  {"env", &Env::perform_and_exit},
  - {"build_external", &BuildExternal::perform_and_exit}
  + {"build-external", &BuildExternal::perform_and_exit}
  };
  return t;
  }
  