Lint markdown files for broken links
Description
It is easy for links in such a big repository to get outdated. Instead of spot-checking those ourselves, use a tool.
Motivation
- Less manual labor
- No broken documentation
Current Implementation
Manual spot checking which is broken:

Related issues
Currently, the links within the root CHANGELOG.md for upgraded workspace crates are broken until we actually make a release because until then, the header in the file contains the unreleased heading.
This may change with https://github.com/libp2p/rust-libp2p/issues/2902 but shouldn't block this issue. I'd suggest that we keep the links working at all times. Having to trim off a couple of -unreleased snippets in the changelog at release time is a simple search and replace operation. Plus, if we have a tool in place that tells you about it, it is almost impossible to forget.
Are you planning to do it yourself in a pull request?
No.
Can we use tool like markdown-link-check or remark-lint to validate links in md files