Referencing documents are not working if .md extension is used

[amimas]

🐛 Bug Report

When referencing other docs using .md extension, Docusaurus is failing to generate a proper link.

Have you read the Contributing Guidelines on issues?

Yes

To Reproduce

(Write your steps here:)

1. Follow the steps mentioned here: https://docusaurus.io/docs/en/navigation#referencing-site-documents
2. Create 2 documents (doc1.md, doc2.md)
3. Create a link in doc1.md ([link to document 2](doc2.md))

Expected behavior

The above steps should generates a proper link to doc2.html in both dev server and also when the site is built for publishing

Actual Behavior

The browser shows an error when clicking on the link in doc1.html

Cannot GET /test-site/docs/doc2.md

When building the site, docusaurus also throws following warnings:

[WARN] unresolved links in file 'doc1.md' > [ 'doc2.md' ]

Reproducible Demo

I will try to create a reproducible demo soon. But, the steps mentioned above are very simple.

[amimas]

This issue was also brought up before in #1137 but not sure why it was closed.

[amimas]

Ooops. Just found my mistake. I had a typo in the doc file name that was being linked to.
Closing it.

[endiliey]

#1137 was fixed by #1138 and hence got closed. I believe this might be a regression.

Edit: Oops, by right it should work