github workflow to validate internal and external links

[negin513]

Our repo, which includes hpc docs is undergoing rapid development and frequent updates and addition.
In this stage of development, ensuring that all internal and external links within docs files are valid and not leading to 404 (or other error) pages is critical to (1) streamline the PR reviews and (2) maintaining the reliability and quality of the docs.

I would suggest:

• Implement a GitHub workflow that automatically validates all internal and external links in the markdown (.md) or other documentation files.

The workflow should be triggered:

1. Every PR and push
2. Nightly in case links changes...

Here is an example for reference.