Customizable pagination buttons

[elixir-1]

• What you're trying to accomplish with this control?
  Pagination buttons at the bottom of each page are a great way to lead readers along of a path of learning. I want to customize this apply only per topic level and not the whole documentation.
  The pagination buttons can act as related readings.

• Specific use cases where you'd want only prev, only next, or neither button?
  Say I have this group called "Test Composer" in my docs, I want people to read the pages in sequence. But I don't care about them actually processing to the next group "Reports" and start reading that as well.

The pagination buttons can act as related readings.

• How you envision the feature working (e.g., frontmatter settings, docs.json configuration)
  I would like a default group level pagination. And to turn it on/off, a docs.json configuration per group.
  To customize it even further, I'd like an option to override docs.json configuration at a page level. This can be a field on each page similar to title, sidebar title.