alwaysOpenInDefaultBranch setting is in README.md, but isn't supported

[james-notion]

The readme shows this custom setting:

  "openInGitHub.alwaysOpenInDefaultBranch": true // if you always work on your local branch, and checking it online will always get 404

But it doesn't seem to be supported by the extension. When I enable it to true, I get the following VSCode warning, and triggering "Open in github" still opens the current branch, not the default branch.

I would really like for this feature to be added!