Document the scope and usage of huborg

[jrgriffiniii]

While https://github.com/samvera-labs/huborg was implemented with a set of features which assist with the automated auditing and updates for Samvera GitHub repositories, this was explicitly created with the intention of keeping huborg from being promoted as a core component.

However, perhaps the could still be some documentation published here outlining its intended usage and feature roadmap in component maintenance.

[jrgriffiniii]

samvera-labs/huborg#25 articulates the call to have this promoted as a core component. Please note that this also justifies this request by referencing the dependency between this project and https://github.com/samvera-labs/huborg