[v2] Improve md interlinking doc / experience

@slorber: it was initially a bug report, what we can improve is here: https://github.com/facebook/docusaurus/issues/2851#issuecomment-642654109

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🐛 Bug Report

Different behavior between ‘.mdx’ and ‘.md’ extensions in markdown link.

• [Button](./docs/Button.md)
• [Button](./docs/Button.mdx)

Have you read the Contributing Guidelines on issues?

yes

To Reproduce

1. In README.md [Button](./docs/Button.mdx)
2. docusaurus start
3. Click Button link.

Expected behavior

Navigate to docs/button same as [Button](./docs/Button.md)

Actual Behavior

It will open a download dialog in chrome 83.

Your Environment

• Docusaurus version used: 2.0.0-alpha.56
• Environment name and version : Chrome 83, Node.js 14
• Operating system and version : desktop

Reproducible Demo

(Paste the link to an example repo, including a siteConfig.js, and exact instructions to reproduce the issue.)

[slorber]

@krillboi when you use <Link/> you provide a path, not a file. Behind, it’s just regular ReactRouter Link, there’s no additional logic.

This path may be created in various ways, not necessarily related to MD files, including using the pages, the addRoute api: https://v2.docusaurus.io/docs/lifecycle-apis/#actions

We resolve MD doc links to their appropriate versioned paths, as a convenient thing for the user to build versioned docs, but we don’t currently do that for link components.

We could make it work, but it’s a whole new feature to design and work on

[cncolder]

@slorber yes. But now I have resolve file path. My docs folder like this:

tree tarojsx.github.io/docs

docs
├── hooks
│   ├── README.md
│   └── docs
│       └── useLogger.mdx
└── ui
    ├── README.md
    └── docs
        └── components
            └── List.mdx

https://github.com/tarojsx/tarojsx.github.io/tree/docusaurus/docs