Document "top-level" bootstrapping

[TheMcMurder]

I've noticed a number of questions about boostrapping 3rd party scripts like split or authorization. I generally respond with a discussion about single-spa utilities, but I realized recently that we're not discussing anywhere in the docs I could find how to initialize/bootstrap those types of dependencies.

I'm thinking about it is the pattern we used at Canopy around having the single-spa root config handle top level bootrapping for things like Sentry, feature toggles, Auth, etc. IIRC we called it spa-boostrapper or something like that.

Is this a pattern we want to encourage or is there a better approach we'd like to suggest?

If we want to encourage this pattern we should probably also update the docs around root-config so that we call out that it's a place to put top level bootstrapping.