Decouple assembler config from docs-builder release process

[bmorelli25]

Summary

We need to be able to release a new version of the docs without having to release a new version of docs-assembler. This will allow us to move quickly and release multiple version updates in quick succession—both of which are often necessary on release days.

If we don't do this, it will require docs eng to be around during releases (and no one wants that 😉 ).

[bmorelli25]

We need to also explore decoupling adding new content sets from the release process. See this slack thread (sorry internal link) for any example of why we want to be able to add new content without creating a new release.