Add Automated Testing for Broken Links in Markdown Files

[MattRudy]

Requesting a new issue to be assigned to me:

Add automated testing to ensure all links in markdown files are not broken, and alert when there are issues with links. As mentioned in #671 , this is already causing problems for anyone viewing your repo.

@sauravjaiswalsj - let me know if you want me to work on this issue or if it's not helpful for your project! I would love to contribute as part of hacktoberfest.