[BUG] embedder-tool README links to missing Embedders documentation

[x-n2o]

Describe the bug

Tools/embedder-tool/README.md links to Libraries/Embedders/README.md, but that file is missing from the main branch (the embedders library moved to the mlx-swift-lm package as MLXEmbedders), so the link resolves to a GitHub 404.

To Reproduce

1. Open Tools/embedder-tool/README.md on main.

2. Find the entry:

   - [Embedders](../../Libraries/Embedders/README.md)

3. Click Embedders.

4. Observe that Libraries/Embedders/README.md is not found.

Expected behavior

The Embedders link should resolve to documentation for the embedders library — for example the MLXEmbedders documentation in mlx-swift-lm.

Desktop (please complete the following information):

• OS Version: N/A
• Device: N/A
• Version: main

Additional context

Surfaced by the markdown link check proposed in #479. Fix in #486.

[x-n2o]

Out-of-repo targets are treated as valid by the link check in #479 (covered by the .check-links-ignore blocklist), so no link rewrite is needed.