Add page override for previous/next links via metadata

[Blendify]

Is your feature request related to a problem? Please describe.
Reading the documentation of Blender, in the building documentation with Linux page I've found that the next button link it's pointing to the building documentation page with MacOs. It would be cool an option to point to other page on previous and next buttons on a single page, so in this case the next button would point to edit manual blender documentation page and the Continue with the next step: Editing. last line could be consistent with Next button.

Describe the solution you'd like
A user should be able to use Special metadata fields to override the previous and next page.

Describe alternatives you've considered
This could be implemented on a theme level for example: readthedocs/sphinx_rtd_theme#995
However, it would be nice if this was a core feature.

Additional context

• Overwrite links of previous and next buttons for a single page readthedocs/sphinx_rtd_theme#921