📦 Add link check action

[TechWiz-3]

In this PR, I have added a workflow which checks links and fails if any of them are broken.

Disclaimer: this action is my own action, the repo is here.

You can view the logs of the workflow on my fork here. 6 links were found to be broken.

Let me know if you'd like me to change anything, any feedback is appreciated either way :)