markdown export

Couldn't sort out how to add something to Trello, adding here.

# Feature request

Markdown export to existing docs (where possible).

## Summary

The idea would be to show a markdown version of a page by using the ".md" extension to url's. This would be an alternative to the HTML view.

Devdocs already has simplified views of documentation, adding an option to view documentation or export documentation in markdown view would add some additional utility. Rather than depending on a conversion from html to markdown, especially in case where a document was originally in markdown.

This would also enable a potential AI integration, where markdown is preferred.

## Examples

I came across another service having the feature: https://www.mintlify.com/docs/ai/markdown-export

The issue does not name any files, tests, or code entry points. Start by tracing how existing documentation pages are served through their HTML URLs, then determine how an .md URL could expose original Markdown where available. Done should include a defined Markdown export behavior for existing documentation and coverage for the relevant page types.

Written by the indexing model from the issue text.