React/Proptypes: Add additional video resource

[scottwright-dev]

Because

This PR adds an additional video resource which provides a brief overview of PropTypes and some various use cases of how to use PropTypes in React.

This PR

• Add a link to the video resource in the Additional Resources section.

Issue

Closes: n/a

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [ ] If this PR addresses an open issue, it is linked in the Issue section
• [x] If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• [x] If any lesson files are included in this PR, they follow the Layout Style Guide