[FR] Improve support for micro-specs

[sserrata]

Is your feature request related to a problem?

In some cases, OpenAPI docs may be split into multiple micro-specs that, collectively, represent a single, logical API. In those cases, each micro-spec will come with its own info section which will also generate a index.api.mdx. When grouping paths by tag, this can lead to filename collisions as each subsequent index.api.mdx file that is generated will overwrite the one prior.

Describe the solution you'd like

The idea would be to extend support for the micro-spec use case by providing an option for defining when multiple specs should be treated as micro-specs and for creating a convention for generating unique "introduction" docs for each tagged group of paths. Additionally, sidebarOptions should be extended to support setting the category link as the "introduction" doc for each respective group.

Describe alternatives you've considered

• Merging micro-specs into a mono-spec.
• Manually creating the sidebar

Additional context

Longer term, it probably makes more sense to transition micro-specs into a mono-spec but there are some cases where this isn't possible or readily feasible.

[sserrata]

#100