Add dark mode for stackges docs

I love this operator, the features, the approach for everything, but i really hate the documentation.

I use to work with dark mode enabled always, since is more comfortable in my opinion, but even browser extensions didn’t handle well the docs page.

Also I want to let you know that the crd documentation is confusing, instead of a lot of tables with the configurations and options, a full crd with all the options written down will be really helpful for new users, like me.

Thanks and congrats for such amazing job!